[AWS SDK for JavaScript V3 API リファレンスガイド](https://docs.aws.amazon.com/AWSJavaScriptSDK/v3/latest/)では、 AWS SDK for JavaScript バージョン3 (V3) のすべての API オペレーションについて詳しく説明します。

翻訳は機械翻訳により提供されています。提供された翻訳内容と英語版の間で齟齬、不一致または矛盾がある場合、英語版が優先します。

# SDK for JavaScript (v3) を使用した DynamoDB の例
<a name="javascript_dynamodb_code_examples"></a>

次のコード例は、DynamoDB で AWS SDK for JavaScript (v3) を使用してアクションを実行し、一般的なシナリオを実装する方法を示しています。

*基本* は、重要なオペレーションをサービス内で実行する方法を示すコード例です。

*アクション*はより大きなプログラムからのコードの抜粋であり、コンテキスト内で実行する必要があります。アクションは個々のサービス機能を呼び出す方法を示していますが、コンテキスト内のアクションは、関連するシナリオで確認できます。

*シナリオ*は、1 つのサービス内から、または他の AWS のサービスと組み合わせて複数の関数を呼び出し、特定のタスクを実行する方法を示すコード例です。

各例には完全なソースコードへのリンクが含まれており、コンテキスト内でコードを設定および実行する方法の手順を確認できます。

**Topics**
+ [はじめに](#get_started)
+ [基本](#basics)
+ [アクション](#actions)
+ [シナリオ](#scenarios)
+ [サーバーレスサンプル](#serverless_examples)

## はじめに
<a name="get_started"></a>

### Hello DynamoDB
<a name="dynamodb_Hello_javascript_topic"></a>

次のコード例は、DynamoDB の使用を開始する方法を示しています。

**SDK for JavaScript (v3)**  
 GitHub には、その他のリソースもあります。用例一覧を検索し、[AWS コード例リポジトリ](https://github.com/awsdocs/aws-doc-sdk-examples/tree/main/javascriptv3/example_code/dynamodb#code-examples)での設定と実行の方法を確認してください。
での DynamoDB の使用の詳細については AWS SDK for JavaScript、[JavaScript を使用した DynamoDB のプログラミング](https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/programming-with-javascript.html)」を参照してください。  

```
import { ListTablesCommand, DynamoDBClient } from "@aws-sdk/client-dynamodb";

const client = new DynamoDBClient({});

export const main = async () => {
  const command = new ListTablesCommand({});

  const response = await client.send(command);
  console.log(response.TableNames.join("\n"));
  return response;
};
```
+  API の詳細については、AWS SDK for JavaScript API リファレンスの**「[ListTables](https://docs.aws.amazon.com/AWSJavaScriptSDK/v3/latest/client/dynamodb/command/ListTablesCommand)」を参照してください。

## 基本
<a name="basics"></a>

### 基本を学ぶ
<a name="dynamodb_Scenario_GettingStartedMovies_javascript_topic"></a>

次のコード例は、以下の操作方法を示しています。
+ 映画データを保持できるテーブルを作成します。
+ テーブルに 1 つの映画を入れ、取得して更新する。
+ サンプル JSON ファイルから映画データをテーブルに書き込む。
+ 特定の年にリリースされた映画を照会する。
+ 一定期間内に公開された映画をスキャンします。
+ テーブルから映画を削除し、テーブルを削除します。

**SDK for JavaScript (v3)**  
 GitHub には、その他のリソースもあります。用例一覧を検索し、[AWS コード例リポジトリ](https://github.com/awsdocs/aws-doc-sdk-examples/tree/main/javascriptv3/example_code/dynamodb#code-examples)での設定と実行の方法を確認してください。

```
import { readFileSync } from "node:fs";
import {
  BillingMode,
  CreateTableCommand,
  DeleteTableCommand,
  DynamoDBClient,
  waitUntilTableExists,
} from "@aws-sdk/client-dynamodb";

/**
 * This module is a convenience library. It abstracts Amazon DynamoDB's data type
 * descriptors (such as S, N, B, and BOOL) by marshalling JavaScript objects into
 * AttributeValue shapes.
 */
import {
  BatchWriteCommand,
  DeleteCommand,
  DynamoDBDocumentClient,
  GetCommand,
  PutCommand,
  UpdateCommand,
  paginateQuery,
  paginateScan,
} from "@aws-sdk/lib-dynamodb";

// These modules are local to our GitHub repository. We recommend cloning
// the project from GitHub if you want to run this example.
// For more information, see https://github.com/awsdocs/aws-doc-sdk-examples.
import { getUniqueName } from "@aws-doc-sdk-examples/lib/utils/util-string.js";
import { dirnameFromMetaUrl } from "@aws-doc-sdk-examples/lib/utils/util-fs.js";
import { chunkArray } from "@aws-doc-sdk-examples/lib/utils/util-array.js";

const dirname = dirnameFromMetaUrl(import.meta.url);
const tableName = getUniqueName("Movies");
const client = new DynamoDBClient({});
const docClient = DynamoDBDocumentClient.from(client);

const log = (msg) => console.log(`[SCENARIO] ${msg}`);

export const main = async () => {
  /**
   * Create a table.
   */

  const createTableCommand = new CreateTableCommand({
    TableName: tableName,
    // This example performs a large write to the database.
    // Set the billing mode to PAY_PER_REQUEST to
    // avoid throttling the large write.
    BillingMode: BillingMode.PAY_PER_REQUEST,
    // Define the attributes that are necessary for the key schema.
    AttributeDefinitions: [
      {
        AttributeName: "year",
        // 'N' is a data type descriptor that represents a number type.
        // For a list of all data type descriptors, see the following link.
        // https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/Programming.LowLevelAPI.html#Programming.LowLevelAPI.DataTypeDescriptors
        AttributeType: "N",
      },
      { AttributeName: "title", AttributeType: "S" },
    ],
    // The KeySchema defines the primary key. The primary key can be
    // a partition key, or a combination of a partition key and a sort key.
    // Key schema design is important. For more info, see
    // https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/best-practices.html
    KeySchema: [
      // The way your data is accessed determines how you structure your keys.
      // The movies table will be queried for movies by year. It makes sense
      // to make year our partition (HASH) key.
      { AttributeName: "year", KeyType: "HASH" },
      { AttributeName: "title", KeyType: "RANGE" },
    ],
  });

  log("Creating a table.");
  const createTableResponse = await client.send(createTableCommand);
  log(`Table created: ${JSON.stringify(createTableResponse.TableDescription)}`);

  // This polls with DescribeTableCommand until the requested table is 'ACTIVE'.
  // You can't write to a table before it's active.
  log("Waiting for the table to be active.");
  await waitUntilTableExists({ client }, { TableName: tableName });
  log("Table active.");

  /**
   * Add a movie to the table.
   */

  log("Adding a single movie to the table.");
  // PutCommand is the first example usage of 'lib-dynamodb'.
  const putCommand = new PutCommand({
    TableName: tableName,
    Item: {
      // In 'client-dynamodb', the AttributeValue would be required (`year: { N: 1981 }`)
      // 'lib-dynamodb' simplifies the usage ( `year: 1981` )
      year: 1981,
      // The preceding KeySchema defines 'title' as our sort (RANGE) key, so 'title'
      // is required.
      title: "The Evil Dead",
      // Every other attribute is optional.
      info: {
        genres: ["Horror"],
      },
    },
  });
  await docClient.send(putCommand);
  log("The movie was added.");

  /**
   * Get a movie from the table.
   */

  log("Getting a single movie from the table.");
  const getCommand = new GetCommand({
    TableName: tableName,
    // Requires the complete primary key. For the movies table, the primary key
    // is only the id (partition key).
    Key: {
      year: 1981,
      title: "The Evil Dead",
    },
    // Set this to make sure that recent writes are reflected.
    // For more information, see https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/HowItWorks.ReadConsistency.html.
    ConsistentRead: true,
  });
  const getResponse = await docClient.send(getCommand);
  log(`Got the movie: ${JSON.stringify(getResponse.Item)}`);

  /**
   * Update a movie in the table.
   */

  log("Updating a single movie in the table.");
  const updateCommand = new UpdateCommand({
    TableName: tableName,
    Key: { year: 1981, title: "The Evil Dead" },
    // This update expression appends "Comedy" to the list of genres.
    // For more information on update expressions, see
    // https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/Expressions.UpdateExpressions.html
    UpdateExpression: "set #i.#g = list_append(#i.#g, :vals)",
    ExpressionAttributeNames: { "#i": "info", "#g": "genres" },
    ExpressionAttributeValues: {
      ":vals": ["Comedy"],
    },
    ReturnValues: "ALL_NEW",
  });
  const updateResponse = await docClient.send(updateCommand);
  log(`Movie updated: ${JSON.stringify(updateResponse.Attributes)}`);

  /**
   * Delete a movie from the table.
   */

  log("Deleting a single movie from the table.");
  const deleteCommand = new DeleteCommand({
    TableName: tableName,
    Key: { year: 1981, title: "The Evil Dead" },
  });
  await docClient.send(deleteCommand);
  log("Movie deleted.");

  /**
   * Upload a batch of movies.
   */

  log("Adding movies from local JSON file.");
  const file = readFileSync(
    `${dirname}../../../../resources/sample_files/movies.json`,
  );
  const movies = JSON.parse(file.toString());
  // chunkArray is a local convenience function. It takes an array and returns
  // a generator function. The generator function yields every N items.
  const movieChunks = chunkArray(movies, 25);
  // For every chunk of 25 movies, make one BatchWrite request.
  for (const chunk of movieChunks) {
    const putRequests = chunk.map((movie) => ({
      PutRequest: {
        Item: movie,
      },
    }));

    const command = new BatchWriteCommand({
      RequestItems: {
        [tableName]: putRequests,
      },
    });

    await docClient.send(command);
  }
  log("Movies added.");

  /**
   * Query for movies by year.
   */

  log("Querying for all movies from 1981.");
  const paginatedQuery = paginateQuery(
    { client: docClient },
    {
      TableName: tableName,
      //For more information about query expressions, see
      // https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/Query.html#Query.KeyConditionExpressions
      KeyConditionExpression: "#y = :y",
      // 'year' is a reserved word in DynamoDB. Indicate that it's an attribute
      // name by using an expression attribute name.
      ExpressionAttributeNames: { "#y": "year" },
      ExpressionAttributeValues: { ":y": 1981 },
      ConsistentRead: true,
    },
  );
  /**
   * @type { Record<string, any>[] };
   */
  const movies1981 = [];
  for await (const page of paginatedQuery) {
    movies1981.push(...page.Items);
  }
  log(`Movies: ${movies1981.map((m) => m.title).join(", ")}`);

  /**
   * Scan the table for movies between 1980 and 1990.
   */

  log("Scan for movies released between 1980 and 1990");
  // A 'Scan' operation always reads every item in the table. If your design requires
  // the use of 'Scan', consider indexing your table or changing your design.
  // https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/bp-query-scan.html
  const paginatedScan = paginateScan(
    { client: docClient },
    {
      TableName: tableName,
      // Scan uses a filter expression instead of a key condition expression. Scan will
      // read the entire table and then apply the filter.
      FilterExpression: "#y between :y1 and :y2",
      ExpressionAttributeNames: { "#y": "year" },
      ExpressionAttributeValues: { ":y1": 1980, ":y2": 1990 },
      ConsistentRead: true,
    },
  );
  /**
   * @type { Record<string, any>[] };
   */
  const movies1980to1990 = [];
  for await (const page of paginatedScan) {
    movies1980to1990.push(...page.Items);
  }
  log(
    `Movies: ${movies1980to1990
      .map((m) => `${m.title} (${m.year})`)
      .join(", ")}`,
  );

  /**
   * Delete the table.
   */

  const deleteTableCommand = new DeleteTableCommand({ TableName: tableName });
  log(`Deleting table ${tableName}.`);
  await client.send(deleteTableCommand);
  log("Table deleted.");
};
```
+ API の詳細については、「*AWS SDK for JavaScript API リファレンス*」の以下のトピックを参照してください。
  + [BatchWriteItem](https://docs.aws.amazon.com/AWSJavaScriptSDK/v3/latest/client/dynamodb/command/BatchWriteItemCommand)
  + [CreateTable](https://docs.aws.amazon.com/AWSJavaScriptSDK/v3/latest/client/dynamodb/command/CreateTableCommand)
  + [DeleteItem](https://docs.aws.amazon.com/AWSJavaScriptSDK/v3/latest/client/dynamodb/command/DeleteItemCommand)
  + [DeleteTable](https://docs.aws.amazon.com/AWSJavaScriptSDK/v3/latest/client/dynamodb/command/DeleteTableCommand)
  + [DescribeTable](https://docs.aws.amazon.com/AWSJavaScriptSDK/v3/latest/client/dynamodb/command/DescribeTableCommand)
  + [GetItem](https://docs.aws.amazon.com/AWSJavaScriptSDK/v3/latest/client/dynamodb/command/GetItemCommand)
  + [PutItem](https://docs.aws.amazon.com/AWSJavaScriptSDK/v3/latest/client/dynamodb/command/PutItemCommand)
  + [Query](https://docs.aws.amazon.com/AWSJavaScriptSDK/v3/latest/client/dynamodb/command/QueryCommand)
  + [Scan](https://docs.aws.amazon.com/AWSJavaScriptSDK/v3/latest/client/dynamodb/command/ScanCommand)
  + [UpdateItem](https://docs.aws.amazon.com/AWSJavaScriptSDK/v3/latest/client/dynamodb/command/UpdateItemCommand)

## アクション
<a name="actions"></a>

### `BatchExecuteStatement`
<a name="dynamodb_BatchExecuteStatement_javascript_topic"></a>

次のコード例は、`BatchExecuteStatement` を使用する方法を示しています。

**SDK for JavaScript (v3)**  
 GitHub には、その他のリソースもあります。用例一覧を検索し、[AWS コード例リポジトリ](https://github.com/awsdocs/aws-doc-sdk-examples/tree/main/javascriptv3/example_code/dynamodb#code-examples)での設定と実行の方法を確認してください。
PartiQL を使用して項目のバッチを作成します。  

```
import { DynamoDBClient } from "@aws-sdk/client-dynamodb";

import {
  DynamoDBDocumentClient,
  BatchExecuteStatementCommand,
} from "@aws-sdk/lib-dynamodb";

const client = new DynamoDBClient({});
const docClient = DynamoDBDocumentClient.from(client);

export const main = async () => {
  const breakfastFoods = ["Eggs", "Bacon", "Sausage"];
  const command = new BatchExecuteStatementCommand({
    Statements: breakfastFoods.map((food) => ({
      Statement: `INSERT INTO BreakfastFoods value {'Name':?}`,
      Parameters: [food],
    })),
  });

  const response = await docClient.send(command);
  console.log(response);
  return response;
};
```
PartiQL を使用して項目のバッチを取得します。  

```
import { DynamoDBClient } from "@aws-sdk/client-dynamodb";

import {
  DynamoDBDocumentClient,
  BatchExecuteStatementCommand,
} from "@aws-sdk/lib-dynamodb";

const client = new DynamoDBClient({});
const docClient = DynamoDBDocumentClient.from(client);

export const main = async () => {
  const command = new BatchExecuteStatementCommand({
    Statements: [
      {
        Statement: "SELECT * FROM PepperMeasurements WHERE Unit=?",
        Parameters: ["Teaspoons"],
        ConsistentRead: true,
      },
      {
        Statement: "SELECT * FROM PepperMeasurements WHERE Unit=?",
        Parameters: ["Grams"],
        ConsistentRead: true,
      },
    ],
  });

  const response = await docClient.send(command);
  console.log(response);
  return response;
};
```
PartiQL を使用して項目のバッチを更新します。  

```
import { DynamoDBClient } from "@aws-sdk/client-dynamodb";

import {
  DynamoDBDocumentClient,
  BatchExecuteStatementCommand,
} from "@aws-sdk/lib-dynamodb";

const client = new DynamoDBClient({});
const docClient = DynamoDBDocumentClient.from(client);

export const main = async () => {
  const eggUpdates = [
    ["duck", "fried"],
    ["chicken", "omelette"],
  ];
  const command = new BatchExecuteStatementCommand({
    Statements: eggUpdates.map((change) => ({
      Statement: "UPDATE Eggs SET Style=? where Variety=?",
      Parameters: [change[1], change[0]],
    })),
  });

  const response = await docClient.send(command);
  console.log(response);
  return response;
};
```
PartiQL を使用して項目のバッチを削除します。  

```
import { DynamoDBClient } from "@aws-sdk/client-dynamodb";

import {
  DynamoDBDocumentClient,
  BatchExecuteStatementCommand,
} from "@aws-sdk/lib-dynamodb";

const client = new DynamoDBClient({});
const docClient = DynamoDBDocumentClient.from(client);

export const main = async () => {
  const command = new BatchExecuteStatementCommand({
    Statements: [
      {
        Statement: "DELETE FROM Flavors where Name=?",
        Parameters: ["Grape"],
      },
      {
        Statement: "DELETE FROM Flavors where Name=?",
        Parameters: ["Strawberry"],
      },
    ],
  });

  const response = await docClient.send(command);
  console.log(response);
  return response;
};
```
+  API の詳細については、AWS SDK for JavaScript API リファレンスの**「[BatchExecuteStatement](https://docs.aws.amazon.com/AWSJavaScriptSDK/v3/latest/client/dynamodb/command/BatchExecuteStatementCommand)」を参照してください。

### `BatchGetItem`
<a name="dynamodb_BatchGetItem_javascript_topic"></a>

次のコード例は、`BatchGetItem` を使用する方法を示しています。

**SDK for JavaScript (v3)**  
 GitHub には、その他のリソースもあります。用例一覧を検索し、[AWS コード例リポジトリ](https://github.com/awsdocs/aws-doc-sdk-examples/tree/main/javascriptv3/example_code/dynamodb#code-examples)での設定と実行の方法を確認してください。
この例では、ドキュメントクライアントを使用して DynamoDB での項目の操作を簡略化しています。API の詳細については、「[BatchGet](https://docs.aws.amazon.com/AWSJavaScriptSDK/v3/latest/Package/-aws-sdk-lib-dynamodb/Class/BatchGetCommand/)」を参照してください。  

```
import { DynamoDBClient } from "@aws-sdk/client-dynamodb";
import { BatchGetCommand, DynamoDBDocumentClient } from "@aws-sdk/lib-dynamodb";

const client = new DynamoDBClient({});
const docClient = DynamoDBDocumentClient.from(client);

export const main = async () => {
  const command = new BatchGetCommand({
    // Each key in this object is the name of a table. This example refers
    // to a Books table.
    RequestItems: {
      Books: {
        // Each entry in Keys is an object that specifies a primary key.
        Keys: [
          {
            Title: "How to AWS",
          },
          {
            Title: "DynamoDB for DBAs",
          },
        ],
        // Only return the "Title" and "PageCount" attributes.
        ProjectionExpression: "Title, PageCount",
      },
    },
  });

  const response = await docClient.send(command);
  console.log(response.Responses.Books);
  return response;
};
```
+  詳細については、「[AWS SDK for JavaScript デベロッパーガイド](https://docs.aws.amazon.com/sdk-for-javascript/v3/developer-guide/dynamodb-example-table-read-write-batch.html#dynamodb-example-table-read-write-batch-reading)」を参照してください。
+  API の詳細については、*AWS SDK for JavaScript API リファレンス*の「[BatchGetItem](https://docs.aws.amazon.com/AWSJavaScriptSDK/v3/latest/client/dynamodb/command/BatchGetItemCommand)」を参照してください。

### `BatchWriteItem`
<a name="dynamodb_BatchWriteItem_javascript_topic"></a>

次のコード例は、`BatchWriteItem` を使用する方法を示しています。

**SDK for JavaScript (v3)**  
 GitHub には、その他のリソースもあります。用例一覧を検索し、[AWS コード例リポジトリ](https://github.com/awsdocs/aws-doc-sdk-examples/tree/main/javascriptv3/example_code/dynamodb#code-examples)での設定と実行の方法を確認してください。
この例では、ドキュメントクライアントを使用して DynamoDB での項目の操作を簡略化しています。API の詳細については、「[BatchWrite](https://docs.aws.amazon.com/AWSJavaScriptSDK/v3/latest/Package/-aws-sdk-lib-dynamodb/Class/BatchWriteCommand/)」を参照してください。  

```
import { DynamoDBClient } from "@aws-sdk/client-dynamodb";
import {
  BatchWriteCommand,
  DynamoDBDocumentClient,
} from "@aws-sdk/lib-dynamodb";
import { readFileSync } from "node:fs";

// These modules are local to our GitHub repository. We recommend cloning
// the project from GitHub if you want to run this example.
// For more information, see https://github.com/awsdocs/aws-doc-sdk-examples.
import { dirnameFromMetaUrl } from "@aws-doc-sdk-examples/lib/utils/util-fs.js";
import { chunkArray } from "@aws-doc-sdk-examples/lib/utils/util-array.js";

const dirname = dirnameFromMetaUrl(import.meta.url);

const client = new DynamoDBClient({});
const docClient = DynamoDBDocumentClient.from(client);

export const main = async () => {
  const file = readFileSync(
    `${dirname}../../../../../resources/sample_files/movies.json`,
  );

  const movies = JSON.parse(file.toString());

  // chunkArray is a local convenience function. It takes an array and returns
  // a generator function. The generator function yields every N items.
  const movieChunks = chunkArray(movies, 25);

  // For every chunk of 25 movies, make one BatchWrite request.
  for (const chunk of movieChunks) {
    const putRequests = chunk.map((movie) => ({
      PutRequest: {
        Item: movie,
      },
    }));

    const command = new BatchWriteCommand({
      RequestItems: {
        // An existing table is required. A composite key of 'title' and 'year' is recommended
        // to account for duplicate titles.
        BatchWriteMoviesTable: putRequests,
      },
    });

    await docClient.send(command);
  }
};
```
+  API の詳細については、*AWS SDK for JavaScript API リファレンス*の「[BatchWriteItem](https://docs.aws.amazon.com/AWSJavaScriptSDK/v3/latest/client/dynamodb/command/BatchWriteItemCommand)」を参照してください。

### `CreateTable`
<a name="dynamodb_CreateTable_javascript_topic"></a>

次のコード例は、`CreateTable` を使用する方法を示しています。

**SDK for JavaScript (v3)**  
 GitHub には、その他のリソースもあります。用例一覧を検索し、[AWS コード例リポジトリ](https://github.com/awsdocs/aws-doc-sdk-examples/tree/main/javascriptv3/example_code/dynamodb#code-examples)での設定と実行の方法を確認してください。

```
import { CreateTableCommand, DynamoDBClient } from "@aws-sdk/client-dynamodb";

const client = new DynamoDBClient({});

export const main = async () => {
  const command = new CreateTableCommand({
    TableName: "EspressoDrinks",
    // For more information about data types,
    // see https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/HowItWorks.NamingRulesDataTypes.html#HowItWorks.DataTypes and
    // https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/Programming.LowLevelAPI.html#Programming.LowLevelAPI.DataTypeDescriptors
    AttributeDefinitions: [
      {
        AttributeName: "DrinkName",
        AttributeType: "S",
      },
    ],
    KeySchema: [
      {
        AttributeName: "DrinkName",
        KeyType: "HASH",
      },
    ],
    BillingMode: "PAY_PER_REQUEST",
  });

  const response = await client.send(command);
  console.log(response);
  return response;
};
```
+  詳細については、「[AWS SDK for JavaScript デベロッパーガイド](https://docs.aws.amazon.com/sdk-for-javascript/v3/developer-guide/dynamodb-examples-using-tables.html#dynamodb-examples-using-tables-creating-a-table)」を参照してください。
+  API の詳細については、*AWS SDK for JavaScript API リファレンス*の「[CreateTable](https://docs.aws.amazon.com/AWSJavaScriptSDK/v3/latest/client/dynamodb/command/CreateTableCommand)」を参照してください。

### `DeleteItem`
<a name="dynamodb_DeleteItem_javascript_topic"></a>

次のコード例は、`DeleteItem` を使用する方法を示しています。

**SDK for JavaScript (v3)**  
 GitHub には、その他のリソースもあります。用例一覧を検索し、[AWS コード例リポジトリ](https://github.com/awsdocs/aws-doc-sdk-examples/tree/main/javascriptv3/example_code/dynamodb#code-examples)での設定と実行の方法を確認してください。
この例では、ドキュメントクライアントを使用して DynamoDB での項目の操作を簡略化しています。API の詳細については、「[DeleteCommand](https://docs.aws.amazon.com/AWSJavaScriptSDK/v3/latest/Package/-aws-sdk-lib-dynamodb/Class/DeleteCommand/)」を参照してください。  

```
import { DynamoDBClient } from "@aws-sdk/client-dynamodb";
import { DynamoDBDocumentClient, DeleteCommand } from "@aws-sdk/lib-dynamodb";

const client = new DynamoDBClient({});
const docClient = DynamoDBDocumentClient.from(client);

export const main = async () => {
  const command = new DeleteCommand({
    TableName: "Sodas",
    Key: {
      Flavor: "Cola",
    },
  });

  const response = await docClient.send(command);
  console.log(response);
  return response;
};
```
+  詳細については、「[AWS SDK for JavaScript デベロッパーガイド](https://docs.aws.amazon.com/sdk-for-javascript/v3/developer-guide/dynamodb-example-table-read-write.html#dynamodb-example-table-read-write-deleting-an-item)」を参照してください。
+  API の詳細については、*AWS SDK for JavaScript API リファレンス*の「[DeleteItem](https://docs.aws.amazon.com/AWSJavaScriptSDK/v3/latest/client/dynamodb/command/DeleteItemCommand)」を参照してください。

### `DeleteTable`
<a name="dynamodb_DeleteTable_javascript_topic"></a>

次のコード例は、`DeleteTable` を使用する方法を示しています。

**SDK for JavaScript (v3)**  
 GitHub には、その他のリソースもあります。用例一覧を検索し、[AWS コード例リポジトリ](https://github.com/awsdocs/aws-doc-sdk-examples/tree/main/javascriptv3/example_code/dynamodb#code-examples)での設定と実行の方法を確認してください。

```
import { DeleteTableCommand, DynamoDBClient } from "@aws-sdk/client-dynamodb";

const client = new DynamoDBClient({});

export const main = async () => {
  const command = new DeleteTableCommand({
    TableName: "DecafCoffees",
  });

  const response = await client.send(command);
  console.log(response);
  return response;
};
```
+  API の詳細については、AWS SDK for JavaScript API リファレンスの**「[DeleteTable](https://docs.aws.amazon.com/AWSJavaScriptSDK/v3/latest/client/dynamodb/command/DeleteTableCommand)」を参照してください。

### `DescribeTable`
<a name="dynamodb_DescribeTable_javascript_topic"></a>

次のコード例は、`DescribeTable` を使用する方法を示しています。

**SDK for JavaScript (v3)**  
 GitHub には、その他のリソースもあります。用例一覧を検索し、[AWS コード例リポジトリ](https://github.com/awsdocs/aws-doc-sdk-examples/tree/main/javascriptv3/example_code/dynamodb#code-examples)での設定と実行の方法を確認してください。

```
import { DescribeTableCommand, DynamoDBClient } from "@aws-sdk/client-dynamodb";

const client = new DynamoDBClient({});

export const main = async () => {
  const command = new DescribeTableCommand({
    TableName: "Pastries",
  });

  const response = await client.send(command);
  console.log(`TABLE NAME: ${response.Table.TableName}`);
  console.log(`TABLE ITEM COUNT: ${response.Table.ItemCount}`);
  return response;
};
```
+  詳細については、「[AWS SDK for JavaScript デベロッパーガイド](https://docs.aws.amazon.com/sdk-for-javascript/v3/developer-guide/dynamodb-examples-using-tables.html#dynamodb-examples-using-tables-describing-a-table)」を参照してください。
+  API の詳細については、*AWS SDK for JavaScript API リファレンス*の「[DescribeTable](https://docs.aws.amazon.com/AWSJavaScriptSDK/v3/latest/client/dynamodb/command/DescribeTableCommand)」を参照してください。

### `DescribeTimeToLive`
<a name="dynamodb_DescribeTimeToLive_javascript_topic"></a>

次のコード例は、`DescribeTimeToLive` を使用する方法を示しています。

**SDK for JavaScript (v3)**  
 AWS SDK for JavaScriptを使用して既存の DynamoDB テーブルの TTL 設定を記述します。  

```
import { DynamoDBClient, DescribeTimeToLiveCommand } from "@aws-sdk/client-dynamodb";

export const describeTTL = async (tableName, region) => {
    const client = new DynamoDBClient({
        region: region,
        endpoint: `https://dynamodb.${region}.amazonaws.com`
    });

    try {
        const ttlDescription = await client.send(new DescribeTimeToLiveCommand({ TableName: tableName }));

        if (ttlDescription.TimeToLiveDescription.TimeToLiveStatus === 'ENABLED') {
            console.log("TTL is enabled for table %s.", tableName);
        } else {
            console.log("TTL is not enabled for table %s.", tableName);
        }

        return ttlDescription;
    } catch (e) {
        console.error(`Error describing table: ${e}`);
        throw e;
    }
}

// Example usage (commented out for testing)
// describeTTL('your-table-name', 'us-east-1');
```
+  API の詳細については、*AWS SDK for JavaScript API リファレンス*の「[DescribeTimeToLive](https://docs.aws.amazon.com/AWSJavaScriptSDK/v3/latest/client/dynamodb/command/DescribeTimeToLiveCommand)」を参照してください。

### `ExecuteStatement`
<a name="dynamodb_ExecuteStatement_javascript_topic"></a>

次のコード例は、`ExecuteStatement` を使用する方法を示しています。

**SDK for JavaScript (v3)**  
 GitHub には、その他のリソースもあります。用例一覧を検索し、[AWS コード例リポジトリ](https://github.com/awsdocs/aws-doc-sdk-examples/tree/main/javascriptv3/example_code/dynamodb#code-examples)での設定と実行の方法を確認してください。
PartiQL を使用して項目を作成します。  

```
import { DynamoDBClient } from "@aws-sdk/client-dynamodb";

import {
  ExecuteStatementCommand,
  DynamoDBDocumentClient,
} from "@aws-sdk/lib-dynamodb";

const client = new DynamoDBClient({});
const docClient = DynamoDBDocumentClient.from(client);

export const main = async () => {
  const command = new ExecuteStatementCommand({
    Statement: `INSERT INTO Flowers value {'Name':?}`,
    Parameters: ["Rose"],
  });

  const response = await docClient.send(command);
  console.log(response);
  return response;
};
```
PartiQL を使用して項目を取得します。  

```
import { DynamoDBClient } from "@aws-sdk/client-dynamodb";

import {
  ExecuteStatementCommand,
  DynamoDBDocumentClient,
} from "@aws-sdk/lib-dynamodb";

const client = new DynamoDBClient({});
const docClient = DynamoDBDocumentClient.from(client);

export const main = async () => {
  const command = new ExecuteStatementCommand({
    Statement: "SELECT * FROM CloudTypes WHERE IsStorm=?",
    Parameters: [false],
    ConsistentRead: true,
  });

  const response = await docClient.send(command);
  console.log(response);
  return response;
};
```
PartiQL を使用して項目を更新します。  

```
import { DynamoDBClient } from "@aws-sdk/client-dynamodb";

import {
  ExecuteStatementCommand,
  DynamoDBDocumentClient,
} from "@aws-sdk/lib-dynamodb";

const client = new DynamoDBClient({});
const docClient = DynamoDBDocumentClient.from(client);

export const main = async () => {
  const command = new ExecuteStatementCommand({
    Statement: "UPDATE EyeColors SET IsRecessive=? where Color=?",
    Parameters: [true, "blue"],
  });

  const response = await docClient.send(command);
  console.log(response);
  return response;
};
```
PartiQL を使用して項目を削除します。  

```
import { DynamoDBClient } from "@aws-sdk/client-dynamodb";

import {
  ExecuteStatementCommand,
  DynamoDBDocumentClient,
} from "@aws-sdk/lib-dynamodb";

const client = new DynamoDBClient({});
const docClient = DynamoDBDocumentClient.from(client);

export const main = async () => {
  const command = new ExecuteStatementCommand({
    Statement: "DELETE FROM PaintColors where Name=?",
    Parameters: ["Purple"],
  });

  const response = await docClient.send(command);
  console.log(response);
  return response;
};
```
+  API の詳細については、*AWS SDK for JavaScript API リファレンス*の[ExecuteStatement](https://docs.aws.amazon.com/AWSJavaScriptSDK/v3/latest/client/dynamodb/command/ExecuteStatementCommand)」を参照してください。

### `GetItem`
<a name="dynamodb_GetItem_javascript_topic"></a>

次のコード例は、`GetItem` を使用する方法を示しています。

**SDK for JavaScript (v3)**  
 GitHub には、その他のリソースもあります。用例一覧を検索し、[AWS コード例リポジトリ](https://github.com/awsdocs/aws-doc-sdk-examples/tree/main/javascriptv3/example_code/dynamodb#code-examples)での設定と実行の方法を確認してください。
この例では、ドキュメントクライアントを使用して DynamoDB での項目の操作を簡略化しています。API の詳細については、「[GetCommand](https://docs.aws.amazon.com/AWSJavaScriptSDK/v3/latest/Package/-aws-sdk-lib-dynamodb/Class/GetCommand/)」を参照してください。  

```
import { DynamoDBClient } from "@aws-sdk/client-dynamodb";
import { DynamoDBDocumentClient, GetCommand } from "@aws-sdk/lib-dynamodb";

const client = new DynamoDBClient({});
const docClient = DynamoDBDocumentClient.from(client);

export const main = async () => {
  const command = new GetCommand({
    TableName: "AngryAnimals",
    Key: {
      CommonName: "Shoebill",
    },
  });

  const response = await docClient.send(command);
  console.log(response);
  return response;
};
```
+  API の詳細については、*AWS SDK for JavaScript API リファレンス*の「[GetItem](https://docs.aws.amazon.com/AWSJavaScriptSDK/v3/latest/client/dynamodb/command/GetItemCommand)」を参照してください。

### `ListTables`
<a name="dynamodb_ListTables_javascript_topic"></a>

次のコード例は、`ListTables` を使用する方法を示しています。

**SDK for JavaScript (v3)**  
 GitHub には、その他のリソースもあります。用例一覧を検索し、[AWS コード例リポジトリ](https://github.com/awsdocs/aws-doc-sdk-examples/tree/main/javascriptv3/example_code/dynamodb#code-examples)での設定と実行の方法を確認してください。

```
import { ListTablesCommand, DynamoDBClient } from "@aws-sdk/client-dynamodb";

const client = new DynamoDBClient({});

export const main = async () => {
  const command = new ListTablesCommand({});

  const response = await client.send(command);
  console.log(response);
  return response;
};
```
+  詳細については、「[AWS SDK for JavaScript デベロッパーガイド](https://docs.aws.amazon.com/sdk-for-javascript/v3/developer-guide/dynamodb-examples-using-tables.html#dynamodb-examples-using-tables-listing-tables)」を参照してください。
+  API の詳細については、*AWS SDK for JavaScript API リファレンス*の「[ListTables](https://docs.aws.amazon.com/AWSJavaScriptSDK/v3/latest/client/dynamodb/command/ListTablesCommand)」を参照してください。

### `PutItem`
<a name="dynamodb_PutItem_javascript_topic"></a>

次のコード例は、`PutItem` を使用する方法を示しています。

**SDK for JavaScript (v3)**  
 GitHub には、その他のリソースもあります。用例一覧を検索し、[AWS コード例リポジトリ](https://github.com/awsdocs/aws-doc-sdk-examples/tree/main/javascriptv3/example_code/dynamodb#code-examples)での設定と実行の方法を確認してください。
この例では、ドキュメントクライアントを使用して DynamoDB での項目の操作を簡略化しています。API の詳細については、「[PutCommand](https://docs.aws.amazon.com/AWSJavaScriptSDK/v3/latest/Package/-aws-sdk-lib-dynamodb/Class/PutCommand/)」を参照してください。  

```
import { DynamoDBClient } from "@aws-sdk/client-dynamodb";
import { PutCommand, DynamoDBDocumentClient } from "@aws-sdk/lib-dynamodb";

const client = new DynamoDBClient({});
const docClient = DynamoDBDocumentClient.from(client);

export const main = async () => {
  const command = new PutCommand({
    TableName: "HappyAnimals",
    Item: {
      CommonName: "Shiba Inu",
    },
  });

  const response = await docClient.send(command);
  console.log(response);
  return response;
};
```
+  API の詳細については、*AWS SDK for JavaScript API リファレンス*の「[PutItem](https://docs.aws.amazon.com/AWSJavaScriptSDK/v3/latest/client/dynamodb/command/PutItemCommand)」を参照してください。

### `Query`
<a name="dynamodb_Query_javascript_topic"></a>

次のコード例は、`Query` を使用する方法を示しています。

**SDK for JavaScript (v3)**  
 GitHub には、その他のリソースもあります。用例一覧を検索し、[AWS コード例リポジトリ](https://github.com/awsdocs/aws-doc-sdk-examples/tree/main/javascriptv3/example_code/dynamodb#code-examples)での設定と実行の方法を確認してください。
この例では、ドキュメントクライアントを使用して DynamoDB での項目の操作を簡略化しています。API の詳細については、「[QueryCommand](https://docs.aws.amazon.com/AWSJavaScriptSDK/v3/latest/Package/-aws-sdk-lib-dynamodb/Class/QueryCommand/)」を参照してください。  

```
import { DynamoDBClient } from "@aws-sdk/client-dynamodb";
import { QueryCommand, DynamoDBDocumentClient } from "@aws-sdk/lib-dynamodb";

const client = new DynamoDBClient({});
const docClient = DynamoDBDocumentClient.from(client);

export const main = async () => {
  const command = new QueryCommand({
    TableName: "CoffeeCrop",
    KeyConditionExpression:
      "OriginCountry = :originCountry AND RoastDate > :roastDate",
    ExpressionAttributeValues: {
      ":originCountry": "Ethiopia",
      ":roastDate": "2023-05-01",
    },
    ConsistentRead: true,
  });

  const response = await docClient.send(command);
  console.log(response);
  return response;
};
```
+  詳細については、「[AWS SDK for JavaScript デベロッパーガイド](https://docs.aws.amazon.com/sdk-for-javascript/v3/developer-guide/dynamodb-example-query-scan.html#dynamodb-example-table-query-scan-querying)」を参照してください。
+  API の詳細については、*AWS SDK for JavaScript API リファレンス*の「[Query](https://docs.aws.amazon.com/AWSJavaScriptSDK/v3/latest/client/dynamodb/command/QueryCommand)」を参照してください。

### `Scan`
<a name="dynamodb_Scan_javascript_topic"></a>

次のコード例は、`Scan` を使用する方法を示しています。

**SDK for JavaScript (v3)**  
 GitHub には、その他のリソースもあります。用例一覧を検索し、[AWS コード例リポジトリ](https://github.com/awsdocs/aws-doc-sdk-examples/tree/main/javascriptv3/example_code/dynamodb#code-examples)での設定と実行の方法を確認してください。
この例では、ドキュメントクライアントを使用して DynamoDB での項目の操作を簡略化しています。API の詳細については、「[ScanCommand](https://docs.aws.amazon.com/AWSJavaScriptSDK/v3/latest/Package/-aws-sdk-lib-dynamodb/Class/ScanCommand/)」を参照してください。  

```
import { DynamoDBClient } from "@aws-sdk/client-dynamodb";
import { DynamoDBDocumentClient, ScanCommand } from "@aws-sdk/lib-dynamodb";

const client = new DynamoDBClient({});
const docClient = DynamoDBDocumentClient.from(client);

export const main = async () => {
  const command = new ScanCommand({
    ProjectionExpression: "#Name, Color, AvgLifeSpan",
    ExpressionAttributeNames: { "#Name": "Name" },
    TableName: "Birds",
  });

  const response = await docClient.send(command);
  for (const bird of response.Items) {
    console.log(`${bird.Name} - (${bird.Color}, ${bird.AvgLifeSpan})`);
  }
  return response;
};
```
+  API の詳細については、*AWS SDK for JavaScript API リファレンス*の「[Scan](https://docs.aws.amazon.com/AWSJavaScriptSDK/v3/latest/client/dynamodb/command/ScanCommand)」を参照してください。

### `UpdateItem`
<a name="dynamodb_UpdateItem_javascript_topic"></a>

次のコード例は、`UpdateItem` を使用する方法を示しています。

**SDK for JavaScript (v3)**  
 GitHub には、その他のリソースもあります。用例一覧を検索し、[AWS コード例リポジトリ](https://github.com/awsdocs/aws-doc-sdk-examples/tree/main/javascriptv3/example_code/dynamodb#code-examples)での設定と実行の方法を確認してください。
この例では、ドキュメントクライアントを使用して DynamoDB での項目の操作を簡略化しています。API の詳細については、「[UpdateCommand](https://docs.aws.amazon.com/AWSJavaScriptSDK/v3/latest/Package/-aws-sdk-lib-dynamodb/Class/UpdateCommand/)」を参照してください。  

```
import { DynamoDBClient } from "@aws-sdk/client-dynamodb";
import { DynamoDBDocumentClient, UpdateCommand } from "@aws-sdk/lib-dynamodb";

const client = new DynamoDBClient({});
const docClient = DynamoDBDocumentClient.from(client);

export const main = async () => {
  const command = new UpdateCommand({
    TableName: "Dogs",
    Key: {
      Breed: "Labrador",
    },
    UpdateExpression: "set Color = :color",
    ExpressionAttributeValues: {
      ":color": "black",
    },
    ReturnValues: "ALL_NEW",
  });

  const response = await docClient.send(command);
  console.log(response);
  return response;
};
```
+  API の詳細については、*AWS SDK for JavaScript API リファレンス*の「[UpdateItem](https://docs.aws.amazon.com/AWSJavaScriptSDK/v3/latest/client/dynamodb/command/UpdateItemCommand)」を参照してください。

### `UpdateTimeToLive`
<a name="dynamodb_UpdateTimeToLive_javascript_topic"></a>

次のコード例は、`UpdateTimeToLive` を使用する方法を示しています。

**SDK for JavaScript (v3)**  
既存の DynamoDB テーブルの TTL を有効にします。  

```
import { DynamoDBClient, UpdateTimeToLiveCommand } from "@aws-sdk/client-dynamodb";

export const enableTTL = async (tableName, ttlAttribute, region = 'us-east-1') => {

    const client = new DynamoDBClient({
        region: region,
        endpoint: `https://dynamodb.${region}.amazonaws.com`
    });

    const params = {
        TableName: tableName,
        TimeToLiveSpecification: {
            Enabled: true,
            AttributeName: ttlAttribute
        }
    };

    try {
        const response = await client.send(new UpdateTimeToLiveCommand(params));
        if (response.$metadata.httpStatusCode === 200) {
            console.log(`TTL enabled successfully for table ${tableName}, using attribute name ${ttlAttribute}.`);
        } else {
            console.log(`Failed to enable TTL for table ${tableName}, response object: ${response}`);
        }
        return response;
    } catch (e) {
        console.error(`Error enabling TTL: ${e}`);
        throw e;
    }
};

// Example usage (commented out for testing)
// enableTTL('ExampleTable', 'exampleTtlAttribute');
```
既存の DynamoDB テーブルの TTL を無効にします。  

```
import { DynamoDBClient, UpdateTimeToLiveCommand } from "@aws-sdk/client-dynamodb";

export const disableTTL = async (tableName, ttlAttribute, region = 'us-east-1') => {

    const client = new DynamoDBClient({
        region: region,
        endpoint: `https://dynamodb.${region}.amazonaws.com`
    });

    const params = {
        TableName: tableName,
        TimeToLiveSpecification: {
            Enabled: false,
            AttributeName: ttlAttribute
        }
    };

    try {
        const response = await client.send(new UpdateTimeToLiveCommand(params));
        if (response.$metadata.httpStatusCode === 200) {
            console.log(`TTL disabled successfully for table ${tableName}, using attribute name ${ttlAttribute}.`);
        } else {
            console.log(`Failed to disable TTL for table ${tableName}, response object: ${response}`);
        }
        return response;
    } catch (e) {
        console.error(`Error disabling TTL: ${e}`);
        throw e;
    }
};

// Example usage (commented out for testing)
// disableTTL('ExampleTable', 'exampleTtlAttribute');
```
+  API の詳細については、*AWS SDK for JavaScript API リファレンス*の「[UpdateTimeToLive](https://docs.aws.amazon.com/AWSJavaScriptSDK/v3/latest/client/dynamodb/command/UpdateTimeToLiveCommand)」を参照してください。

## シナリオ
<a name="scenarios"></a>

### DynamoDB テーブルにデータを送信するアプリケーションを構築する
<a name="cross_SubmitDataApp_javascript_topic"></a>

次のコード例は、Amazon DynamoDB テーブルにデータを送信し、ユーザーがテーブルを更新したときに通知するアプリケーションを構築する方法を示しています。

**SDK for JavaScript (v3)**  
 この例では、ユーザーが Amazon DynamoDB テーブルにデータを送信し、Amazon Simple Notification Service (Amazon SNS) を使用して管理者にテキストメッセージを送信できるようにするアプリを構築する方法を示します。  
 完全なソースコードとセットアップおよび実行の手順については、[GitHub](https://github.com/awsdocs/aws-doc-sdk-examples/tree/main/javascriptv3/example_code/cross-services/submit-data-app) で完全な例を参照してください。  
この例は、[AWS SDK for JavaScript v3 デベロッパーガイド](https://docs.aws.amazon.com/sdk-for-javascript/v3/developer-guide/cross-service-example-submitting-data.html)でも使用できます。  

**この例で使用されているサービス**
+ DynamoDB
+ Amazon SNS

### 複数の値を 1 つの属性と比較する
<a name="dynamodb_Scenario_CompareMultipleValues_javascript_topic"></a>

次のコード例は、DynamoDB で複数の値を 1 つの属性と比較する方法を示しています。
+ IN 演算子を使用して、複数の値を 1 つの属性と比較します。
+ IN 演算子を複数の OR 条件と比較します。
+ IN の使用によるパフォーマンスと式の複雑さのメリットを理解します。

**SDK for JavaScript (v3)**  
を使用して、複数の値を単一の属性と比較します AWS SDK for JavaScript。  

```
const { DynamoDBClient } = require("@aws-sdk/client-dynamodb");
const { 
  DynamoDBDocumentClient, 
  ScanCommand, 
  QueryCommand 
} = require("@aws-sdk/lib-dynamodb");

/**
 * Query or scan a DynamoDB table to find items where an attribute matches any value from a list.
 * 
 * This function demonstrates the use of the IN operator to compare a single attribute
 * against multiple possible values, which is more efficient than using multiple OR conditions.
 * 
 * @param {Object} config - AWS configuration object
 * @param {string} tableName - The name of the DynamoDB table
 * @param {string} attributeName - The name of the attribute to compare against the values list
 * @param {Array} valuesList - List of values to compare the attribute against
 * @param {string} [partitionKeyName] - Optional name of the partition key attribute for query operations
 * @param {string} [partitionKeyValue] - Optional value of the partition key to query
 * @returns {Promise<Object>} - The response from DynamoDB containing the matching items
 */
async function compareMultipleValues(
  config,
  tableName,
  attributeName,
  valuesList,
  partitionKeyName,
  partitionKeyValue
) {
  // Initialize the DynamoDB client
  const client = new DynamoDBClient(config);
  const docClient = DynamoDBDocumentClient.from(client);
  
  // Create the filter expression using the IN operator
  const filterExpression = `${attributeName} IN (${valuesList.map((_, index) => `:val${index}`).join(', ')})`;
  
  // Create expression attribute values for the values list
  const expressionAttributeValues = valuesList.reduce((acc, val, index) => {
    acc[`:val${index}`] = val;
    return acc;
  }, {});
  
  // If partition key is provided, perform a query operation
  if (partitionKeyName && partitionKeyValue) {
    const keyCondition = `${partitionKeyName} = :partitionKey`;
    expressionAttributeValues[':partitionKey'] = partitionKeyValue;
    
    // Initialize array to collect all items
    let allItems = [];
    let lastEvaluatedKey;
    
    // Use pagination to get all results
    do {
      const params = {
        TableName: tableName,
        KeyConditionExpression: keyCondition,
        FilterExpression: filterExpression,
        ExpressionAttributeValues: expressionAttributeValues
      };
      
      // Add ExclusiveStartKey if we have a lastEvaluatedKey from a previous query
      if (lastEvaluatedKey) {
        params.ExclusiveStartKey = lastEvaluatedKey;
      }
      
      const response = await docClient.send(new QueryCommand(params));
      
      // Add the items from this page to our collection
      if (response.Items && response.Items.length > 0) {
        allItems = [...allItems, ...response.Items];
      }
      
      // Get the key for the next page of results
      lastEvaluatedKey = response.LastEvaluatedKey;
    } while (lastEvaluatedKey);
    
    // Return the complete result
    return {
      Items: allItems,
      Count: allItems.length
    };
  } else {
    // Otherwise, perform a scan operation
    // Initialize array to collect all items
    let allItems = [];
    let lastEvaluatedKey;
    
    // Use pagination to get all results
    do {
      const params = {
        TableName: tableName,
        FilterExpression: filterExpression,
        ExpressionAttributeValues: expressionAttributeValues
      };
      
      // Add ExclusiveStartKey if we have a lastEvaluatedKey from a previous scan
      if (lastEvaluatedKey) {
        params.ExclusiveStartKey = lastEvaluatedKey;
      }
      
      const response = await docClient.send(new ScanCommand(params));
      
      // Add the items from this page to our collection
      if (response.Items && response.Items.length > 0) {
        allItems = [...allItems, ...response.Items];
      }
      
      // Get the key for the next page of results
      lastEvaluatedKey = response.LastEvaluatedKey;
    } while (lastEvaluatedKey);
    
    // Return the complete result
    return {
      Items: allItems,
      Count: allItems.length
    };
  }
}

/**
 * Alternative implementation using multiple OR conditions instead of the IN operator.
 * 
 * This function is provided for comparison to show why using the IN operator is preferable.
 * With many values, this approach becomes verbose and less efficient.
 * 
 * @param {Object} config - AWS configuration object
 * @param {string} tableName - The name of the DynamoDB table
 * @param {string} attributeName - The name of the attribute to compare against the values list
 * @param {Array} valuesList - List of values to compare the attribute against
 * @param {string} [partitionKeyName] - Optional name of the partition key attribute for query operations
 * @param {string} [partitionKeyValue] - Optional value of the partition key to query
 * @returns {Promise<Object>} - The response from DynamoDB containing the matching items
 */
async function compareWithOrConditions(
  config,
  tableName,
  attributeName,
  valuesList,
  partitionKeyName,
  partitionKeyValue
) {
  // Initialize the DynamoDB client
  const client = new DynamoDBClient(config);
  const docClient = DynamoDBDocumentClient.from(client);
  
  // If no values provided, return empty result
  if (!valuesList || valuesList.length === 0) {
    return {
      Items: [],
      Count: 0
    };
  }
  
  // Create the filter expression using multiple OR conditions
  const filterConditions = valuesList.map((_, index) => `${attributeName} = :val${index}`);
  const filterExpression = filterConditions.join(' OR ');
  
  // Create expression attribute values for the values list
  const expressionAttributeValues = valuesList.reduce((acc, val, index) => {
    acc[`:val${index}`] = val;
    return acc;
  }, {});
  
  // If partition key is provided, perform a query operation
  if (partitionKeyName && partitionKeyValue) {
    const keyCondition = `${partitionKeyName} = :partitionKey`;
    expressionAttributeValues[':partitionKey'] = partitionKeyValue;
    
    // Initialize array to collect all items
    let allItems = [];
    let lastEvaluatedKey;
    
    // Use pagination to get all results
    do {
      const params = {
        TableName: tableName,
        KeyConditionExpression: keyCondition,
        FilterExpression: filterExpression,
        ExpressionAttributeValues: expressionAttributeValues
      };
      
      // Add ExclusiveStartKey if we have a lastEvaluatedKey from a previous query
      if (lastEvaluatedKey) {
        params.ExclusiveStartKey = lastEvaluatedKey;
      }
      
      const response = await docClient.send(new QueryCommand(params));
      
      // Add the items from this page to our collection
      if (response.Items && response.Items.length > 0) {
        allItems = [...allItems, ...response.Items];
      }
      
      // Get the key for the next page of results
      lastEvaluatedKey = response.LastEvaluatedKey;
    } while (lastEvaluatedKey);
    
    // Return the complete result
    return {
      Items: allItems,
      Count: allItems.length
    };
  } else {
    // Otherwise, perform a scan operation
    // Initialize array to collect all items
    let allItems = [];
    let lastEvaluatedKey;
    
    // Use pagination to get all results
    do {
      const params = {
        TableName: tableName,
        FilterExpression: filterExpression,
        ExpressionAttributeValues: expressionAttributeValues
      };
      
      // Add ExclusiveStartKey if we have a lastEvaluatedKey from a previous scan
      if (lastEvaluatedKey) {
        params.ExclusiveStartKey = lastEvaluatedKey;
      }
      
      const response = await docClient.send(new ScanCommand(params));
      
      // Add the items from this page to our collection
      if (response.Items && response.Items.length > 0) {
        allItems = [...allItems, ...response.Items];
      }
      
      // Get the key for the next page of results
      lastEvaluatedKey = response.LastEvaluatedKey;
    } while (lastEvaluatedKey);
    
    // Return the complete result
    return {
      Items: allItems,
      Count: allItems.length
    };
  }
}
```
複数の値と を比較する使用例 AWS SDK for JavaScript。  

```
/**
 * Example of how to use the compareMultipleValues function.
 */
async function exampleUsage() {
  // Example parameters
  const config = { region: "us-west-2" };
  const tableName = "Products";
  const attributeName = "Category";
  const valuesList = ["Electronics", "Computers", "Accessories"];
  
  console.log(`Searching for products in any of these categories: ${valuesList.join(', ')}`);
  
  try {
    // Using the IN operator (recommended approach)
    console.log("\nApproach 1: Using the IN operator");
    const response = await compareMultipleValues(
      config,
      tableName,
      attributeName,
      valuesList
    );
    
    console.log(`Found ${response.Count} products in the specified categories`);
    
    // Using multiple OR conditions (alternative approach)
    console.log("\nApproach 2: Using multiple OR conditions");
    const response2 = await compareWithOrConditions(
      config,
      tableName,
      attributeName,
      valuesList
    );
    
    console.log(`Found ${response2.Count} products in the specified categories`);
    
    // Example with a query operation
    console.log("\nQuerying a specific manufacturer's products in multiple categories");
    const partitionKeyName = "Manufacturer";
    const partitionKeyValue = "Acme";
    
    const response3 = await compareMultipleValues(
      config,
      tableName,
      attributeName,
      valuesList,
      partitionKeyName,
      partitionKeyValue
    );
    
    console.log(`Found ${response3.Count} Acme products in the specified categories`);
    
    // Explain the benefits of using the IN operator
    console.log("\nBenefits of using the IN operator:");
    console.log("1. More concise expression compared to multiple OR conditions");
    console.log("2. Better readability and maintainability");
    console.log("3. Potentially better performance with large value lists");
    console.log("4. Simpler code that's less prone to errors");
    console.log("5. Easier to modify when adding or removing values");
    
  } catch (error) {
    console.error("Error:", error);
  }
}
```
+ API の詳細については、「*AWS SDK for JavaScript API リファレンス*」の以下のトピックを参照してください。
  + [Query](https://docs.aws.amazon.com/AWSJavaScriptSDK/v3/latest/client/dynamodb/command/QueryCommand)
  + [Scan](https://docs.aws.amazon.com/AWSJavaScriptSDK/v3/latest/client/dynamodb/command/ScanCommand)

### 項目の TTL を条件付きで更新する
<a name="dynamodb_UpdateItemConditionalTTL_javascript_topic"></a>

以下のコード例は、項目の TTL を条件付きで更新する方法を示しています。

**SDK for JavaScript (v3)**  
条件を指定して、テーブル内の既存の DynamoDB 項目の TTL を更新します。  

```
import { DynamoDBClient, UpdateItemCommand } from "@aws-sdk/client-dynamodb";
import { marshall, unmarshall } from "@aws-sdk/util-dynamodb";

export const updateItemConditional = async (tableName, partitionKey, sortKey, region = 'us-east-1', newAttribute = 'default-value') => {
    const client = new DynamoDBClient({
        region: region,
        endpoint: `https://dynamodb.${region}.amazonaws.com`
    });

    const currentTime = Math.floor(Date.now() / 1000);

    const params = {
        TableName: tableName,
        Key: marshall({
            artist: partitionKey,
            album: sortKey
        }),
        UpdateExpression: "SET newAttribute = :newAttribute",
        ConditionExpression: "expireAt > :expiration",
        ExpressionAttributeValues: marshall({
            ':newAttribute': newAttribute,
            ':expiration': currentTime
        }),
        ReturnValues: "ALL_NEW"
    };

    try {
        const response = await client.send(new UpdateItemCommand(params));
        const responseData = unmarshall(response.Attributes);
        console.log("Item updated successfully: ", responseData);
        return responseData;
    } catch (error) {
        if (error.name === "ConditionalCheckFailedException") {
            console.log("Condition check failed: Item's 'expireAt' is expired.");
        } else {
            console.error("Error updating item: ", error);
        }
        throw error;
    }
};

// Example usage (commented out for testing)
// updateItemConditional('your-table-name', 'your-partition-key-value', 'your-sort-key-value');
```
+  API の詳細については、*AWS SDK for JavaScript API リファレンス*の「[UpdateItem](https://docs.aws.amazon.com/AWSJavaScriptSDK/v3/latest/client/dynamodb/command/UpdateItemCommand)」を参照してください。

### 式演算子をカウントする
<a name="dynamodb_Scenario_ExpressionOperatorCounting_javascript_topic"></a>

次のコード例は、DynamoDB で式演算子をカウントする方法を示しています。
+ DynamoDB の演算子の制限数が 300 であることを理解します。
+ 複雑な式での演算子をカウントする。
+ 式を最適化して制限内に収まるようにします。

**SDK for JavaScript (v3)**  
 AWS SDK for JavaScriptを使用して式演算子のカウントをデモンストレーションします。  

```
const { DynamoDBClient } = require("@aws-sdk/client-dynamodb");
const { 
  DynamoDBDocumentClient, 
  UpdateCommand,
  QueryCommand
} = require("@aws-sdk/lib-dynamodb");

/**
 * Create a complex filter expression with a specified number of conditions.
 * 
 * This function demonstrates how to generate a complex expression with
 * a specific number of operators to test the 300 operator limit.
 * 
 * @param {number} conditionsCount - Number of conditions to include
 * @param {boolean} useAnd - Whether to use AND (true) or OR (false) between conditions
 * @returns {Object} - Object containing the filter expression and attribute values
 */
function createComplexFilterExpression(conditionsCount, useAnd = true) {
  // Initialize the expression parts and attribute values
  const conditions = [];
  const expressionAttributeValues = {};
  
  // Generate the specified number of conditions
  for (let i = 0; i < conditionsCount; i++) {
    // Alternate between different comparison operators for variety
    let condition;
    const valueKey = `:val${i}`;
    
    switch (i % 5) {
      case 0:
        condition = `attribute${i} = ${valueKey}`;
        expressionAttributeValues[valueKey] = `value${i}`;
        break;
      case 1:
        condition = `attribute${i} > ${valueKey}`;
        expressionAttributeValues[valueKey] = i;
        break;
      case 2:
        condition = `attribute${i} < ${valueKey}`;
        expressionAttributeValues[valueKey] = i * 10;
        break;
      case 3:
        condition = `contains(attribute${i}, ${valueKey})`;
        expressionAttributeValues[valueKey] = `substring${i}`;
        break;
      case 4:
        condition = `attribute_exists(attribute${i})`;
        break;
    }
    
    conditions.push(condition);
  }
  
  // Join the conditions with AND or OR
  const operator = useAnd ? " AND " : " OR ";
  const filterExpression = conditions.join(operator);
  
  // Calculate the operator count
  // Each condition has 1 operator (=, >, <, contains, attribute_exists)
  // Each AND or OR between conditions is 1 operator
  const operatorCount = conditionsCount + (conditionsCount > 0 ? conditionsCount - 1 : 0);
  
  return {
    filterExpression,
    expressionAttributeValues,
    operatorCount
  };
}

/**
 * Create a complex update expression with a specified number of operations.
 * 
 * This function demonstrates how to generate a complex update expression with
 * a specific number of operators to test the 300 operator limit.
 * 
 * @param {number} operationsCount - Number of operations to include
 * @returns {Object} - Object containing the update expression and attribute values
 */
function createComplexUpdateExpression(operationsCount) {
  // Initialize the expression parts and attribute values
  const setOperations = [];
  const expressionAttributeValues = {};
  
  // Generate the specified number of SET operations
  for (let i = 0; i < operationsCount; i++) {
    // Alternate between different types of SET operations
    let operation;
    const valueKey = `:val${i}`;
    
    switch (i % 3) {
      case 0:
        // Simple assignment (1 operator: =)
        operation = `attribute${i} = ${valueKey}`;
        expressionAttributeValues[valueKey] = `value${i}`;
        break;
      case 1:
        // Addition (2 operators: = and +)
        operation = `attribute${i} = attribute${i} + ${valueKey}`;
        expressionAttributeValues[valueKey] = i;
        break;
      case 2:
        // Conditional assignment with if_not_exists (2 operators: = and if_not_exists)
        operation = `attribute${i} = if_not_exists(attribute${i}, ${valueKey})`;
        expressionAttributeValues[valueKey] = i * 10;
        break;
    }
    
    setOperations.push(operation);
  }
  
  // Create the update expression
  const updateExpression = `SET ${setOperations.join(", ")}`;
  
  // Calculate the operator count
  // Each operation has 1-2 operators as noted above
  let operatorCount = 0;
  for (let i = 0; i < operationsCount; i++) {
    operatorCount += (i % 3 === 0) ? 1 : 2;
  }
  
  return {
    updateExpression,
    expressionAttributeValues,
    operatorCount
  };
}

/**
 * Test the operator limit by attempting an operation with a complex expression.
 * 
 * This function demonstrates what happens when an expression approaches or
 * exceeds the 300 operator limit.
 * 
 * @param {Object} config - AWS configuration object
 * @param {string} tableName - The name of the DynamoDB table
 * @param {Object} key - The key of the item to update
 * @param {number} operatorCount - Target number of operators to include
 * @returns {Promise<Object>} - Result of the operation attempt
 */
async function testOperatorLimit(
  config,
  tableName,
  key,
  operatorCount
) {
  // Initialize the DynamoDB client
  const client = new DynamoDBClient(config);
  const docClient = DynamoDBDocumentClient.from(client);
  
  // Create a complex update expression with the specified operator count
  const { updateExpression, expressionAttributeValues, operatorCount: actualCount } = 
    createComplexUpdateExpression(Math.ceil(operatorCount / 1.5)); // Adjust to get close to target count
  
  console.log(`Generated update expression with approximately ${actualCount} operators`);
  
  // Define the update parameters
  const params = {
    TableName: tableName,
    Key: key,
    UpdateExpression: updateExpression,
    ExpressionAttributeValues: expressionAttributeValues,
    ReturnValues: "UPDATED_NEW"
  };
  
  try {
    // Attempt the update operation
    const response = await docClient.send(new UpdateCommand(params));
    return {
      success: true,
      message: `Operation succeeded with ${actualCount} operators`,
      data: response
    };
  } catch (error) {
    // Check if the error is due to exceeding the operator limit
    if (error.name === "ValidationException" && 
        error.message.includes("too many operators")) {
      return {
        success: false,
        message: `Operation failed: ${error.message}`,
        operatorCount: actualCount
      };
    }
    
    // Return other errors
    return {
      success: false,
      message: `Operation failed: ${error.message}`,
      error
    };
  }
}

/**
 * Break down a complex expression into multiple simpler operations.
 * 
 * This function demonstrates how to handle expressions that would exceed
 * the 300 operator limit by breaking them into multiple operations.
 * 
 * @param {Object} config - AWS configuration object
 * @param {string} tableName - The name of the DynamoDB table
 * @param {Object} key - The key of the item to update
 * @param {number} totalOperations - Total number of operations to perform
 * @returns {Promise<Object>} - Result of the operations
 */
async function breakDownComplexExpression(
  config,
  tableName,
  key,
  totalOperations
) {
  // Initialize the DynamoDB client
  const client = new DynamoDBClient(config);
  const docClient = DynamoDBDocumentClient.from(client);
  
  // Calculate how many operations we can safely include in each batch
  // Using 150 as a conservative limit (well below 300)
  const operationsPerBatch = 100;
  const batchCount = Math.ceil(totalOperations / operationsPerBatch);
  
  console.log(`Breaking down ${totalOperations} operations into ${batchCount} batches`);
  
  const results = [];
  
  // Process each batch
  for (let batch = 0; batch < batchCount; batch++) {
    // Calculate the operations for this batch
    const batchStart = batch * operationsPerBatch;
    const batchEnd = Math.min(batchStart + operationsPerBatch, totalOperations);
    const batchSize = batchEnd - batchStart;
    
    console.log(`Processing batch ${batch + 1}/${batchCount} with ${batchSize} operations`);
    
    // Create an update expression for this batch
    const { updateExpression, expressionAttributeValues, operatorCount } = 
      createComplexUpdateExpression(batchSize);
    
    // Define the update parameters
    const params = {
      TableName: tableName,
      Key: key,
      UpdateExpression: updateExpression,
      ExpressionAttributeValues: expressionAttributeValues,
      ReturnValues: "UPDATED_NEW"
    };
    
    try {
      // Perform the update operation for this batch
      const response = await docClient.send(new UpdateCommand(params));
      
      results.push({
        batch: batch + 1,
        success: true,
        operatorCount,
        attributes: response.Attributes
      });
    } catch (error) {
      results.push({
        batch: batch + 1,
        success: false,
        operatorCount,
        error: error.message
      });
      
      // Stop processing if an error occurs
      break;
    }
  }
  
  return {
    totalBatches: batchCount,
    results
  };
}

/**
 * Count operators in a DynamoDB expression based on the rules in the documentation.
 * 
 * This function demonstrates how operators are counted according to the
 * DynamoDB documentation.
 * 
 * @param {string} expression - The DynamoDB expression to analyze
 * @returns {Object} - Breakdown of operator counts
 */
function countOperatorsInExpression(expression) {
  // Initialize counters for different operator types
  const counts = {
    comparisonOperators: 0,
    logicalOperators: 0,
    functions: 0,
    arithmeticOperators: 0,
    specialOperators: 0,
    total: 0
  };
  
  // Count comparison operators (=, <>, <, <=, >, >=)
  const comparisonRegex = /[^<>]=[^=]|<>|<=|>=|[^<]>[^=]|[^>]<[^=]/g;
  const comparisonMatches = expression.match(comparisonRegex) || [];
  counts.comparisonOperators = comparisonMatches.length;
  
  // Count logical operators (AND, OR, NOT)
  const andMatches = expression.match(/\bAND\b/g) || [];
  const orMatches = expression.match(/\bOR\b/g) || [];
  const notMatches = expression.match(/\bNOT\b/g) || [];
  counts.logicalOperators = andMatches.length + orMatches.length + notMatches.length;
  
  // Count functions (attribute_exists, attribute_not_exists, attribute_type, begins_with, contains, size)
  const functionRegex = /\b(attribute_exists|attribute_not_exists|attribute_type|begins_with|contains|size|if_not_exists)\(/g;
  const functionMatches = expression.match(functionRegex) || [];
  counts.functions = functionMatches.length;
  
  // Count arithmetic operators (+ and -)
  const arithmeticMatches = expression.match(/[a-zA-Z0-9_)\]]\s*[\+\-]\s*[a-zA-Z0-9_(:]/g) || [];
  counts.arithmeticOperators = arithmeticMatches.length;
  
  // Count special operators (BETWEEN, IN)
  const betweenMatches = expression.match(/\bBETWEEN\b/g) || [];
  const inMatches = expression.match(/\bIN\b/g) || [];
  counts.specialOperators = betweenMatches.length + inMatches.length;
  
  // Add extra operators for BETWEEN (each BETWEEN includes an AND)
  counts.logicalOperators += betweenMatches.length;
  
  // Calculate total
  counts.total = counts.comparisonOperators + 
                 counts.logicalOperators + 
                 counts.functions + 
                 counts.arithmeticOperators + 
                 counts.specialOperators;
  
  return counts;
}
```
でカウントする式演算子の使用例 AWS SDK for JavaScript。  

```
/**
 * Example of how to work with expression operator counting.
 */
async function exampleUsage() {
  // Example parameters
  const config = { region: "us-west-2" };
  const tableName = "Products";
  const key = { ProductId: "P12345" };
  
  console.log("Demonstrating DynamoDB expression operator counting and the 300 operator limit");
  
  try {
    // Example 1: Analyze a simple expression
    console.log("\nExample 1: Analyzing a simple expression");
    const simpleExpression = "Price = :price AND Rating > :rating AND Category IN (:cat1, :cat2, :cat3)";
    const simpleCount = countOperatorsInExpression(simpleExpression);
    
    console.log(`Expression: ${simpleExpression}`);
    console.log("Operator count breakdown:");
    console.log(`- Comparison operators: ${simpleCount.comparisonOperators}`);
    console.log(`- Logical operators: ${simpleCount.logicalOperators}`);
    console.log(`- Functions: ${simpleCount.functions}`);
    console.log(`- Arithmetic operators: ${simpleCount.arithmeticOperators}`);
    console.log(`- Special operators: ${simpleCount.specialOperators}`);
    console.log(`- Total operators: ${simpleCount.total}`);
    
    // Example 2: Analyze a complex expression
    console.log("\nExample 2: Analyzing a complex expression");
    const complexExpression = 
      "(attribute_exists(Category) AND Size BETWEEN :min AND :max) OR " +
      "(Price > :price AND contains(Description, :keyword) AND " +
      "(Rating >= :minRating OR Reviews > :minReviews))";
    const complexCount = countOperatorsInExpression(complexExpression);
    
    console.log(`Expression: ${complexExpression}`);
    console.log("Operator count breakdown:");
    console.log(`- Comparison operators: ${complexCount.comparisonOperators}`);
    console.log(`- Logical operators: ${complexCount.logicalOperators}`);
    console.log(`- Functions: ${complexCount.functions}`);
    console.log(`- Arithmetic operators: ${complexCount.arithmeticOperators}`);
    console.log(`- Special operators: ${complexCount.specialOperators}`);
    console.log(`- Total operators: ${complexCount.total}`);
    
    // Example 3: Test approaching the operator limit
    console.log("\nExample 3: Testing an expression approaching the operator limit");
    const approachingLimit = await testOperatorLimit(config, tableName, key, 290);
    console.log(approachingLimit.message);
    
    // Example 4: Test exceeding the operator limit
    console.log("\nExample 4: Testing an expression exceeding the operator limit");
    const exceedingLimit = await testOperatorLimit(config, tableName, key, 310);
    console.log(exceedingLimit.message);
    
    // Example 5: Breaking down a complex expression
    console.log("\nExample 5: Breaking down a complex expression into multiple operations");
    const breakdownResult = await breakDownComplexExpression(config, tableName, key, 500);
    console.log(`Processed ${breakdownResult.results.length} of ${breakdownResult.totalBatches} batches`);
    
    // Explain the operator counting rules
    console.log("\nKey points about DynamoDB expression operator counting:");
    console.log("1. The maximum number of operators in any expression is 300");
    console.log("2. Each comparison operator (=, <>, <, <=, >, >=) counts as 1 operator");
    console.log("3. Each logical operator (AND, OR, NOT) counts as 1 operator");
    console.log("4. Each function call (attribute_exists, contains, etc.) counts as 1 operator");
    console.log("5. Each arithmetic operator (+ or -) counts as 1 operator");
    console.log("6. BETWEEN counts as 2 operators (BETWEEN itself and the AND within it)");
    console.log("7. IN counts as 1 operator regardless of the number of values");
    console.log("8. Parentheses for grouping and attribute paths don't count as operators");
    console.log("9. When you exceed the limit, the error always reports '301 operators'");
    console.log("10. For complex operations, break them into multiple smaller operations");
    
  } catch (error) {
    console.error("Error:", error);
  }
}
```
+  API の詳細については、*AWS SDK for JavaScript API リファレンス*の「[UpdateItem](https://docs.aws.amazon.com/AWSJavaScriptSDK/v3/latest/client/dynamodb/command/UpdateItemCommand)」を参照してください。

### サーバーレスアプリケーションを作成して写真を管理する
<a name="cross_PAM_javascript_topic"></a>

次のコード例では、ユーザーがラベルを使用して写真を管理できるサーバーレスアプリケーションを作成する方法について示しています。

**SDK for JavaScript (v3)**  
 Amazon Rekognition を使用して画像内のラベルを検出し、保存して後で取得できるようにする写真アセット管理アプリケーションの開発方法を示します。  
完全なソースコードと設定および実行の手順については、[GitHub](https://github.com/awsdocs/aws-doc-sdk-examples/tree/main/javascriptv3/example_code/cross-services/photo-asset-manager) で完全な例を参照してください。  
この例のソースについて詳しくは、[AWS  コミュニティ](https://community.aws/posts/cloud-journeys/01-serverless-image-recognition-app)でブログ投稿を参照してください。  

**この例で使用されているサービス**
+ API ゲートウェイ
+ DynamoDB
+ Lambda
+ Amazon Rekognition
+ Amazon S3
+ Amazon SNS

### ウォームスループットを有効にしたテーブルを作成する
<a name="dynamodb_CreateTableWarmThroughput_javascript_topic"></a>

次のコード例は、ウォームスループットを有効にしたテーブルを作成する方法を示しています。

**SDK for JavaScript (v3)**  
 AWS SDK for JavaScriptを使用してウォームスループット設定を含む DynamoDB テーブルを作成します。  

```
import { DynamoDBClient, CreateTableCommand } from "@aws-sdk/client-dynamodb";

export async function createDynamoDBTableWithWarmThroughput(
  tableName,
  partitionKey,
  sortKey,
  miscKeyAttr,
  nonKeyAttr,
  tableProvisionedReadUnits,
  tableProvisionedWriteUnits,
  tableWarmReads,
  tableWarmWrites,
  indexName,
  indexProvisionedReadUnits,
  indexProvisionedWriteUnits,
  indexWarmReads,
  indexWarmWrites,
  region = "us-east-1"
) {
  try {
    const ddbClient = new DynamoDBClient({ region: region });
    const command = new CreateTableCommand({
      TableName: tableName,
      AttributeDefinitions: [
          { AttributeName: partitionKey, AttributeType: "S" },
          { AttributeName: sortKey, AttributeType: "S" },
          { AttributeName: miscKeyAttr, AttributeType: "N" },
      ],
      KeySchema: [
          { AttributeName: partitionKey, KeyType: "HASH" },
          { AttributeName: sortKey, KeyType: "RANGE" },
      ],
      ProvisionedThroughput: {
          ReadCapacityUnits: tableProvisionedReadUnits,
          WriteCapacityUnits: tableProvisionedWriteUnits,
      },
      WarmThroughput: {
          ReadUnitsPerSecond: tableWarmReads,
          WriteUnitsPerSecond: tableWarmWrites,
      },
      GlobalSecondaryIndexes: [
          {
            IndexName: indexName,
            KeySchema: [
                { AttributeName: sortKey, KeyType: "HASH" },
                { AttributeName: miscKeyAttr, KeyType: "RANGE" },
            ],
            Projection: {
                ProjectionType: "INCLUDE",
                NonKeyAttributes: [nonKeyAttr],
            },
            ProvisionedThroughput: {
                ReadCapacityUnits: indexProvisionedReadUnits,
                WriteCapacityUnits: indexProvisionedWriteUnits,
            },
            WarmThroughput: {
                ReadUnitsPerSecond: indexWarmReads,
                WriteUnitsPerSecond: indexWarmWrites,
            },
          },
      ],
    });
    const response = await ddbClient.send(command);
    console.log(response);
    return response;
  } catch (error) {
    console.error(`Error creating table: ${error}`);
    throw error;
  }
}

// Example usage (commented out for testing)
/*
createDynamoDBTableWithWarmThroughput(
  'example-table',
  'pk',
  'sk',
  'gsiKey',
  'data',
  10, 10, 5, 5,
  'example-index',
  5, 5, 2, 2
);
*/
```
+  API の詳細については、*AWS SDK for JavaScript API リファレンス*の「[CreateTable](https://docs.aws.amazon.com/AWSJavaScriptSDK/v3/latest/client/dynamodb/command/CreateTableCommand)」を参照してください。

### TTL を含む項目を作成する
<a name="dynamodb_PutItemTTL_javascript_topic"></a>

次のコード例は、TTL を含む項目の作成方法を示しています。

**SDK for JavaScript (v3)**  

```
import { DynamoDBClient, PutItemCommand } from "@aws-sdk/client-dynamodb";

export function createDynamoDBItem(table_name, region, partition_key, sort_key) {
    const client = new DynamoDBClient({
        region: region,
        endpoint: `https://dynamodb.${region}.amazonaws.com`
    });

    // Get the current time in epoch second format
    const current_time = Math.floor(new Date().getTime() / 1000);

    // Calculate the expireAt time (90 days from now) in epoch second format
    const expire_at = Math.floor((new Date().getTime() + 90 * 24 * 60 * 60 * 1000) / 1000);

    // Create DynamoDB item
    const item = {
        'partitionKey': {'S': partition_key},
        'sortKey': {'S': sort_key},
        'createdAt': {'N': current_time.toString()},
        'expireAt': {'N': expire_at.toString()}
    };

    const putItemCommand = new PutItemCommand({
        TableName: table_name,
        Item: item,
        ProvisionedThroughput: {
            ReadCapacityUnits: 1,
            WriteCapacityUnits: 1,
        },
    });

    client.send(putItemCommand, function(err, data) {
        if (err) {
            console.log("Exception encountered when creating item %s, here's what happened: ", data, err);
            throw err;
        } else {
            console.log("Item created successfully: %s.", data);
            return data;
        }
    });
}

// Example usage (commented out for testing)
// createDynamoDBItem('your-table-name', 'us-east-1', 'your-partition-key-value', 'your-sort-key-value');
```
+  API の詳細については、*AWS SDK for JavaScript API リファレンス*の「[PutItem](https://docs.aws.amazon.com/AWSJavaScriptSDK/v3/latest/client/dynamodb/command/PutItemCommand)」を参照してください。

### PartiQL DELETE を使用してデータを削除する
<a name="dynamodb_PartiQLDelete_javascript_topic"></a>

次のコード例は、PartiQL DELETE ステートメントを使用してデータを削除する方法を示しています。

**SDK for JavaScript (v3)**  
PartiQL DELETE ステートメントを使用して、DynamoDB テーブルから項目を削除します AWS SDK for JavaScript。  

```
/**
 * This example demonstrates how to delete items from a DynamoDB table using PartiQL.
 * It shows different ways to delete documents with various index types.
 */
import { DynamoDBClient } from "@aws-sdk/client-dynamodb";
import {
  DynamoDBDocumentClient,
  ExecuteStatementCommand,
  BatchExecuteStatementCommand,
} from "@aws-sdk/lib-dynamodb";

/**
 * Delete a single item by its partition key using PartiQL.
 * 
 * @param tableName - The name of the DynamoDB table
 * @param partitionKeyName - The name of the partition key attribute
 * @param partitionKeyValue - The value of the partition key
 * @returns The response from the ExecuteStatementCommand
 */
export const deleteItemByPartitionKey = async (
  tableName: string,
  partitionKeyName: string,
  partitionKeyValue: string | number
) => {
  const client = new DynamoDBClient({});
  const docClient = DynamoDBDocumentClient.from(client);

  const params = {
    Statement: `DELETE FROM "${tableName}" WHERE ${partitionKeyName} = ?`,
    Parameters: [partitionKeyValue],
  };

  try {
    const data = await docClient.send(new ExecuteStatementCommand(params));
    console.log("Item deleted successfully");
    return data;
  } catch (err) {
    console.error("Error deleting item:", err);
    throw err;
  }
};

/**
 * Delete an item by its composite key (partition key + sort key) using PartiQL.
 * 
 * @param tableName - The name of the DynamoDB table
 * @param partitionKeyName - The name of the partition key attribute
 * @param partitionKeyValue - The value of the partition key
 * @param sortKeyName - The name of the sort key attribute
 * @param sortKeyValue - The value of the sort key
 * @returns The response from the ExecuteStatementCommand
 */
export const deleteItemByCompositeKey = async (
  tableName: string,
  partitionKeyName: string,
  partitionKeyValue: string | number,
  sortKeyName: string,
  sortKeyValue: string | number
) => {
  const client = new DynamoDBClient({});
  const docClient = DynamoDBDocumentClient.from(client);

  const params = {
    Statement: `DELETE FROM "${tableName}" WHERE ${partitionKeyName} = ? AND ${sortKeyName} = ?`,
    Parameters: [partitionKeyValue, sortKeyValue],
  };

  try {
    const data = await docClient.send(new ExecuteStatementCommand(params));
    console.log("Item deleted successfully");
    return data;
  } catch (err) {
    console.error("Error deleting item:", err);
    throw err;
  }
};

/**
 * Delete an item with a condition to ensure the delete only happens if a condition is met.
 * 
 * @param tableName - The name of the DynamoDB table
 * @param partitionKeyName - The name of the partition key attribute
 * @param partitionKeyValue - The value of the partition key
 * @param conditionAttribute - The attribute to check in the condition
 * @param conditionValue - The value to compare against in the condition
 * @returns The response from the ExecuteStatementCommand
 */
export const deleteItemWithCondition = async (
  tableName: string,
  partitionKeyName: string,
  partitionKeyValue: string | number,
  conditionAttribute: string,
  conditionValue: any
) => {
  const client = new DynamoDBClient({});
  const docClient = DynamoDBDocumentClient.from(client);

  const params = {
    Statement: `DELETE FROM "${tableName}" WHERE ${partitionKeyName} = ? AND ${conditionAttribute} = ?`,
    Parameters: [partitionKeyValue, conditionValue],
  };

  try {
    const data = await docClient.send(new ExecuteStatementCommand(params));
    console.log("Item deleted with condition successfully");
    return data;
  } catch (err) {
    console.error("Error deleting item with condition:", err);
    throw err;
  }
};

/**
 * Batch delete multiple items using PartiQL.
 * 
 * @param tableName - The name of the DynamoDB table
 * @param keys - Array of objects containing key information
 * @returns The response from the BatchExecuteStatementCommand
 */
export const batchDeleteItems = async (
  tableName: string,
  keys: Array<{
    partitionKeyName: string;
    partitionKeyValue: string | number;
    sortKeyName?: string;
    sortKeyValue?: string | number;
  }>
) => {
  const client = new DynamoDBClient({});
  const docClient = DynamoDBDocumentClient.from(client);

  // Create statements for each delete
  const statements = keys.map((key) => {
    if (key.sortKeyName && key.sortKeyValue !== undefined) {
      return {
        Statement: `DELETE FROM "${tableName}" WHERE ${key.partitionKeyName} = ? AND ${key.sortKeyName} = ?`,
        Parameters: [key.partitionKeyValue, key.sortKeyValue],
      };
    } else {
      return {
        Statement: `DELETE FROM "${tableName}" WHERE ${key.partitionKeyName} = ?`,
        Parameters: [key.partitionKeyValue],
      };
    }
  });

  const params = {
    Statements: statements,
  };

  try {
    const data = await docClient.send(new BatchExecuteStatementCommand(params));
    console.log("Items batch deleted successfully");
    return data;
  } catch (err) {
    console.error("Error batch deleting items:", err);
    throw err;
  }
};

/**
 * Delete multiple items that match a filter condition.
 * Note: This performs a scan operation which can be expensive on large tables.
 * 
 * @param tableName - The name of the DynamoDB table
 * @param filterAttribute - The attribute to filter on
 * @param filterValue - The value to filter by
 * @returns The response from the ExecuteStatementCommand
 */
export const deleteItemsByFilter = async (
  tableName: string,
  filterAttribute: string,
  filterValue: any
) => {
  const client = new DynamoDBClient({});
  const docClient = DynamoDBDocumentClient.from(client);

  const params = {
    Statement: `DELETE FROM "${tableName}" WHERE ${filterAttribute} = ?`,
    Parameters: [filterValue],
  };

  try {
    const data = await docClient.send(new ExecuteStatementCommand(params));
    console.log("Items deleted by filter successfully");
    return data;
  } catch (err) {
    console.error("Error deleting items by filter:", err);
    throw err;
  }
};

/**
 * Example usage showing how to delete items with different index types
 */
export const deleteExamples = async () => {
  // Delete an item by partition key (simple primary key)
  await deleteItemByPartitionKey("UsersTable", "userId", "user123");

  // Delete an item by composite key (partition key + sort key)
  await deleteItemByCompositeKey(
    "OrdersTable",
    "orderId",
    "order456",
    "productId",
    "prod789"
  );

  // Delete with a condition
  await deleteItemWithCondition(
    "UsersTable",
    "userId",
    "user789",
    "userStatus",
    "inactive"
  );

  // Batch delete multiple items
  await batchDeleteItems("UsersTable", [
    { partitionKeyName: "userId", partitionKeyValue: "user234" },
    { partitionKeyName: "userId", partitionKeyValue: "user345" },
  ]);

  // Batch delete items with composite keys
  await batchDeleteItems("OrdersTable", [
    {
      partitionKeyName: "orderId",
      partitionKeyValue: "order567",
      sortKeyName: "productId",
      sortKeyValue: "prod123",
    },
    {
      partitionKeyName: "orderId",
      partitionKeyValue: "order678",
      sortKeyName: "productId",
      sortKeyValue: "prod456",
    },
  ]);

  // Delete items by filter (use with caution)
  await deleteItemsByFilter("UsersTable", "userStatus", "deleted");
};
```
+ API の詳細については、「*AWS SDK for JavaScript API リファレンス*」の以下のトピックを参照してください。
  + [BatchExecuteStatement](https://docs.aws.amazon.com/AWSJavaScriptSDK/v3/latest/client/dynamodb/command/BatchExecuteStatementCommand)
  + [ExecuteStatement](https://docs.aws.amazon.com/AWSJavaScriptSDK/v3/latest/client/dynamodb/command/ExecuteStatementCommand)

### PartiQL INSERT を使用してデータを挿入する
<a name="dynamodb_PartiQLInsert_javascript_topic"></a>

次のコード例は、PartiQL INSERT ステートメントを使用してデータを挿入する方法を示しています。

**SDK for JavaScript (v3)**  
PartiQL INSERT ステートメントを使用して、DynamoDB テーブルに項目を挿入します AWS SDK for JavaScript。  

```
/**
 * This example demonstrates how to insert items into a DynamoDB table using PartiQL.
 * It shows different ways to insert documents with various index types.
 */
import { DynamoDBClient } from "@aws-sdk/client-dynamodb";
import {
  DynamoDBDocumentClient,
  ExecuteStatementCommand,
  BatchExecuteStatementCommand,
} from "@aws-sdk/lib-dynamodb";

/**
 * Insert a single item into a DynamoDB table using PartiQL.
 * 
 * @param tableName - The name of the DynamoDB table
 * @param item - The item to insert
 * @returns The response from the ExecuteStatementCommand
 */
export const insertItem = async (tableName: string, item: Record<string, any>) => {
  const client = new DynamoDBClient({});
  const docClient = DynamoDBDocumentClient.from(client);

  // Convert the item to a string representation for PartiQL
  const itemString = JSON.stringify(item).replace(/"([^"]+)":/g, '$1:');

  const params = {
    Statement: `INSERT INTO "${tableName}" VALUE ${itemString}`,
  };

  try {
    const data = await docClient.send(new ExecuteStatementCommand(params));
    console.log("Item inserted successfully");
    return data;
  } catch (err) {
    console.error("Error inserting item:", err);
    throw err;
  }
};

/**
 * Insert multiple items into a DynamoDB table using PartiQL batch operation.
 * This is more efficient than inserting items one by one.
 * 
 * @param tableName - The name of the DynamoDB table
 * @param items - Array of items to insert
 * @returns The response from the BatchExecuteStatementCommand
 */
export const batchInsertItems = async (tableName: string, items: Record<string, any>[]) => {
  const client = new DynamoDBClient({});
  const docClient = DynamoDBDocumentClient.from(client);

  // Create statements for each item
  const statements = items.map((item) => {
    const itemString = JSON.stringify(item).replace(/"([^"]+)":/g, '$1:');
    return {
      Statement: `INSERT INTO "${tableName}" VALUE ${itemString}`,
    };
  });

  const params = {
    Statements: statements,
  };

  try {
    const data = await docClient.send(new BatchExecuteStatementCommand(params));
    console.log("Items inserted successfully");
    return data;
  } catch (err) {
    console.error("Error batch inserting items:", err);
    throw err;
  }
};

/**
 * Insert an item with a condition to prevent overwriting existing items.
 * This is useful for ensuring you don't accidentally overwrite data.
 * 
 * @param tableName - The name of the DynamoDB table
 * @param item - The item to insert
 * @param partitionKeyName - The name of the partition key attribute
 * @returns The response from the ExecuteStatementCommand
 */
export const insertItemWithCondition = async (
  tableName: string,
  item: Record<string, any>,
  partitionKeyName: string
) => {
  const client = new DynamoDBClient({});
  const docClient = DynamoDBDocumentClient.from(client);

  const itemString = JSON.stringify(item).replace(/"([^"]+)":/g, '$1:');
  const partitionKeyValue = JSON.stringify(item[partitionKeyName]);

  const params = {
    Statement: `INSERT INTO "${tableName}" VALUE ${itemString} WHERE attribute_not_exists(${partitionKeyName})`,
    Parameters: [{ S: partitionKeyValue }],
  };

  try {
    const data = await docClient.send(new ExecuteStatementCommand(params));
    console.log("Item inserted with condition successfully");
    return data;
  } catch (err) {
    console.error("Error inserting item with condition:", err);
    throw err;
  }
};

/**
 * Example usage showing how to insert items with different index types
 */
export const insertExamples = async () => {
  // Example table with a simple primary key (just partition key)
  const simpleKeyItem = {
    userId: "user123",
    name: "John Doe",
    email: "john@example.com",
  };
  await insertItem("UsersTable", simpleKeyItem);

  // Example table with composite key (partition key + sort key)
  const compositeKeyItem = {
    orderId: "order456",
    productId: "prod789",
    quantity: 2,
    price: 29.99,
  };
  await insertItem("OrdersTable", compositeKeyItem);

  // Example with Global Secondary Index (GSI)
  // The GSI might be on the email attribute
  const gsiItem = {
    userId: "user789",
    email: "jane@example.com",
    name: "Jane Smith",
    userType: "premium",  // This could be part of a GSI
  };
  await insertItem("UsersTable", gsiItem);

  // Example with Local Secondary Index (LSI)
  // LSI uses the same partition key but different sort key
  const lsiItem = {
    orderId: "order567",  // Partition key
    productId: "prod123", // Sort key for the table
    orderDate: "2023-11-15", // Potential sort key for an LSI
    quantity: 1,
    price: 19.99,
  };
  await insertItem("OrdersTable", lsiItem);

  // Batch insert example with multiple items
  const batchItems = [
    {
      userId: "user234",
      name: "Alice Johnson",
      email: "alice@example.com",
    },
    {
      userId: "user345",
      name: "Bob Williams",
      email: "bob@example.com",
    },
  ];
  await batchInsertItems("UsersTable", batchItems);
};
```
+ API の詳細については、「*AWS SDK for JavaScript API リファレンス*」の以下のトピックを参照してください。
  + [BatchExecuteStatement](https://docs.aws.amazon.com/AWSJavaScriptSDK/v3/latest/client/dynamodb/command/BatchExecuteStatementCommand)
  + [ExecuteStatement](https://docs.aws.amazon.com/AWSJavaScriptSDK/v3/latest/client/dynamodb/command/ExecuteStatementCommand)

### ブラウザからの Lambda 関数の呼び出し
<a name="cross_LambdaForBrowser_javascript_topic"></a>

次のコード例は、ブラウザから AWS Lambda 関数を呼び出す方法を示しています。

**SDK for JavaScript (v3)**  
 AWS Lambda 関数を使用して Amazon DynamoDB テーブルをユーザー選択で更新するブラウザベースのアプリケーションを作成できます。このアプリは v3 AWS SDK for JavaScript を使用します。  
 完全なソースコードとセットアップおよび実行の手順については、[GitHub](https://github.com/awsdocs/aws-doc-sdk-examples/tree/main/javascriptv3/example_code/cross-services/lambda-for-browser) で完全な例を参照してください。  

**この例で使用されているサービス**
+ DynamoDB
+ Lambda

### 高度なクエリオペレーションを実行する
<a name="dynamodb_Scenario_AdvancedQueryTechniques_javascript_topic"></a>

次のコード例は、DynamoDB で高度なクエリオペレーションを実行する方法を示しています。
+ さまざまなフィルタリングと条件の手法を使用してテーブルをクエリします。
+ 大きな結果セットのページ分割を実装します。
+ 代替アクセスパターンにはグローバルセカンダリインデックスを使用します。
+ アプリケーション要件に基づいて整合性コントロールを適用します。

**SDK for JavaScript (v3)**  
を使用した強力な整合性のある読み取りによるクエリ AWS SDK for JavaScript。  

```
const { DynamoDBClient, QueryCommand } = require("@aws-sdk/client-dynamodb");

/**
 * Queries a DynamoDB table with configurable read consistency
 * 
 * @param {Object} config - AWS SDK configuration object
 * @param {string} tableName - The name of the DynamoDB table
 * @param {string} partitionKeyName - The name of the partition key
 * @param {string} partitionKeyValue - The value of the partition key
 * @param {boolean} useConsistentRead - Whether to use strongly consistent reads
 * @returns {Promise<Object>} - The query response
 */
async function queryWithConsistentRead(
  config,
  tableName,
  partitionKeyName,
  partitionKeyValue,
  useConsistentRead = false
) {
  try {
    // Create DynamoDB client
    const client = new DynamoDBClient(config);

    // Construct the query input
    const input = {
      TableName: tableName,
      KeyConditionExpression: "#pk = :pkValue",
      ExpressionAttributeNames: {
        "#pk": partitionKeyName
      },
      ExpressionAttributeValues: {
        ":pkValue": { S: partitionKeyValue }
      },
      ConsistentRead: useConsistentRead
    };

    // Execute the query
    const command = new QueryCommand(input);
    return await client.send(command);
  } catch (error) {
    console.error(`Error querying with consistent read: ${error}`);
    throw error;
  }
}
```
でグローバルセカンダリインデックスを使用してクエリを実行します AWS SDK for JavaScript。  

```
const { DynamoDBClient, QueryCommand } = require("@aws-sdk/client-dynamodb");

/**
 * Queries a DynamoDB table using the primary key
 * 
 * @param {Object} config - AWS SDK configuration object
 * @param {string} tableName - The name of the DynamoDB table
 * @param {string} userId - The user ID to query by (partition key)
 * @returns {Promise<Object>} - The query response
 */
async function queryTable(
  config,
  tableName,
  userId
) {
  try {
    // Create DynamoDB client
    const client = new DynamoDBClient(config);

    // Construct the query input for the base table
    const input = {
      TableName: tableName,
      KeyConditionExpression: "user_id = :userId",
      ExpressionAttributeValues: {
        ":userId": { S: userId }
      }
    };

    // Execute the query
    const command = new QueryCommand(input);
    return await client.send(command);
  } catch (error) {
    console.error(`Error querying table: ${error}`);
    throw error;
  }
}

/**
 * Queries a DynamoDB Global Secondary Index (GSI)
 * 
 * @param {Object} config - AWS SDK configuration object
 * @param {string} tableName - The name of the DynamoDB table
 * @param {string} indexName - The name of the GSI to query
 * @param {string} gameId - The game ID to query by (GSI partition key)
 * @returns {Promise<Object>} - The query response
 */
async function queryGSI(
  config,
  tableName,
  indexName,
  gameId
) {
  try {
    // Create DynamoDB client
    const client = new DynamoDBClient(config);

    // Construct the query input for the GSI
    const input = {
      TableName: tableName,
      IndexName: indexName,
      KeyConditionExpression: "game_id = :gameId",
      ExpressionAttributeValues: {
        ":gameId": { S: gameId }
      }
    };

    // Execute the query
    const command = new QueryCommand(input);
    return await client.send(command);
  } catch (error) {
    console.error(`Error querying GSI: ${error}`);
    throw error;
  }
}
```
を使用してページ分割でクエリを実行します AWS SDK for JavaScript。  

```
/**
 * Example demonstrating how to handle large query result sets in DynamoDB using pagination
 * 
 * This example shows:
 * - How to use pagination to handle large result sets
 * - How to use LastEvaluatedKey to retrieve the next page of results
 * - How to construct subsequent query requests using ExclusiveStartKey
 */
const { DynamoDBClient, QueryCommand } = require("@aws-sdk/client-dynamodb");

/**
 * Queries a DynamoDB table with pagination to handle large result sets
 * 
 * @param {Object} config - AWS SDK configuration object
 * @param {string} tableName - The name of the DynamoDB table
 * @param {string} partitionKeyName - The name of the partition key
 * @param {string} partitionKeyValue - The value of the partition key
 * @param {number} pageSize - Number of items per page
 * @returns {Promise<Array>} - All items from the query
 */
async function queryWithPagination(
  config,
  tableName,
  partitionKeyName,
  partitionKeyValue,
  pageSize = 25
) {
  try {
    // Create DynamoDB client
    const client = new DynamoDBClient(config);
    
    // Initialize variables for pagination
    let lastEvaluatedKey = undefined;
    const allItems = [];
    let pageCount = 0;
    
    // Loop until all pages are retrieved
    do {
      // Construct the query input
      const input = {
        TableName: tableName,
        KeyConditionExpression: "#pk = :pkValue",
        Limit: pageSize,
        ExpressionAttributeNames: {
          "#pk": partitionKeyName
        },
        ExpressionAttributeValues: {
          ":pkValue": { S: partitionKeyValue }
        }
      };
      
      // Add ExclusiveStartKey if we have a LastEvaluatedKey from a previous query
      if (lastEvaluatedKey) {
        input.ExclusiveStartKey = lastEvaluatedKey;
      }
      
      // Execute the query
      const command = new QueryCommand(input);
      const response = await client.send(command);
      
      // Process the current page of results
      pageCount++;
      console.log(`Processing page ${pageCount} with ${response.Items.length} items`);
      
      // Add the items from this page to our collection
      if (response.Items && response.Items.length > 0) {
        allItems.push(...response.Items);
      }
      
      // Get the LastEvaluatedKey for the next page
      lastEvaluatedKey = response.LastEvaluatedKey;
      
    } while (lastEvaluatedKey); // Continue until there are no more pages
    
    console.log(`Query complete. Retrieved ${allItems.length} items in ${pageCount} pages.`);
    return allItems;
  } catch (error) {
    console.error(`Error querying with pagination: ${error}`);
    throw error;
  }
}

/**
 * Example usage:
 * 
 * // Query all items in the "AWS DynamoDB" forum with pagination
 * const allItems = await queryWithPagination(
 *   { region: "us-west-2" },
 *   "ForumThreads",
 *   "ForumName",
 *   "AWS DynamoDB",
 *   25 // 25 items per page
 * );
 * 
 * console.log(`Total items retrieved: ${allItems.length}`);
 * 
 * // Notes on pagination:
 * // - LastEvaluatedKey contains the primary key of the last evaluated item
 * // - When LastEvaluatedKey is undefined/null, there are no more items to retrieve
 * // - ExclusiveStartKey tells DynamoDB where to start the next page
 * // - Pagination helps manage memory usage for large result sets
 * // - Each page requires a separate network request to DynamoDB
 */

module.exports = { queryWithPagination };
```
を使用して複雑なフィルターでクエリを実行します AWS SDK for JavaScript。  

```
const { DynamoDBClient, QueryCommand } = require("@aws-sdk/client-dynamodb");

/**
 * Queries a DynamoDB table with a complex filter expression
 * 
 * @param {Object} config - AWS SDK configuration object
 * @param {string} tableName - The name of the DynamoDB table
 * @param {string} partitionKeyName - The name of the partition key
 * @param {string} partitionKeyValue - The value of the partition key
 * @param {number|string} minViews - Minimum number of views for filtering
 * @param {number|string} minReplies - Minimum number of replies for filtering
 * @param {string} requiredTag - Tag that must be present in the item's tags set
 * @returns {Promise<Object>} - The query response
 */
async function queryWithComplexFilter(
  config,
  tableName,
  partitionKeyName,
  partitionKeyValue,
  minViews,
  minReplies,
  requiredTag
) {
  try {
    // Create DynamoDB client
    const client = new DynamoDBClient(config);

    // Construct the query input
    const input = {
      TableName: tableName,
      KeyConditionExpression: "#pk = :pkValue",
      FilterExpression: "views >= :minViews AND replies >= :minReplies AND contains(tags, :tag)",
      ExpressionAttributeNames: {
        "#pk": partitionKeyName
      },
      ExpressionAttributeValues: {
        ":pkValue": { S: partitionKeyValue },
        ":minViews": { N: minViews.toString() },
        ":minReplies": { N: minReplies.toString() },
        ":tag": { S: requiredTag }
      }
    };

    // Execute the query
    const command = new QueryCommand(input);
    return await client.send(command);
  } catch (error) {
    console.error(`Error querying with complex filter: ${error}`);
    throw error;
  }
}
```
を使用して動的に構築されたフィルター式でクエリを実行します AWS SDK for JavaScript。  

```
const { DynamoDBClient, QueryCommand } = require("@aws-sdk/client-dynamodb");

async function queryWithDynamicFilter(
  config,
  tableName,
  partitionKeyName,
  partitionKeyValue,
  sortKeyName,
  sortKeyValue,
  filterParams = {}
) {
  try {
    // Create DynamoDB client
    const client = new DynamoDBClient(config);

    // Initialize filter expression components
    let filterExpressions = [];
    const expressionAttributeValues = {
      ":pkValue": { S: partitionKeyValue },
      ":skValue": { S: sortKeyValue }
    };
    const expressionAttributeNames = {
      "#pk": partitionKeyName,
      "#sk": sortKeyName
    };

    // Add status filter if provided
    if (filterParams.status) {
      filterExpressions.push("status = :status");
      expressionAttributeValues[":status"] = { S: filterParams.status };
    }

    // Add minimum views filter if provided
    if (filterParams.minViews !== undefined) {
      filterExpressions.push("views >= :minViews");
      expressionAttributeValues[":minViews"] = { N: filterParams.minViews.toString() };
    }

    // Add author filter if provided
    if (filterParams.author) {
      filterExpressions.push("author = :author");
      expressionAttributeValues[":author"] = { S: filterParams.author };
    }

    // Construct the query input
    const input = {
      TableName: tableName,
      KeyConditionExpression: "#pk = :pkValue AND #sk = :skValue"
    };

    // Add filter expression if any filters were provided
    if (filterExpressions.length > 0) {
      input.FilterExpression = filterExpressions.join(" AND ");
    }

    // Add expression attribute names and values
    input.ExpressionAttributeNames = expressionAttributeNames;
    input.ExpressionAttributeValues = expressionAttributeValues;

    // Execute the query
    const command = new QueryCommand(input);
    return await client.send(command);
  } catch (error) {
    console.error(`Error querying with dynamic filter: ${error}`);
    throw error;
  }
}
```
+  API の詳細については、*AWS SDK for JavaScript API リファレンス*の「[Query](https://docs.aws.amazon.com/AWSJavaScriptSDK/v3/latest/client/dynamodb/command/QueryCommand)」を参照してください。

### リストオペレーションを実行する
<a name="dynamodb_Scenario_ListOperations_javascript_topic"></a>

次のコード例は、DynamoDB でリストオペレーションを実行する方法を示しています。
+ リスト属性に要素を追加します。
+ リスト属性から要素を削除します。
+ インデックスでリスト内の特定の要素を更新します。
+ リスト追加関数およびリストインデックス関数を使用します。

**SDK for JavaScript (v3)**  
を使用してリストオペレーションをデモンストレーションします AWS SDK for JavaScript。  

```
const { DynamoDBClient } = require("@aws-sdk/client-dynamodb");
const { 
  DynamoDBDocumentClient, 
  UpdateCommand,
  GetCommand,
  PutCommand
} = require("@aws-sdk/lib-dynamodb");

/**
 * Append elements to a list attribute.
 * 
 * This function demonstrates how to use the list_append function to add elements
 * to the end of a list.
 * 
 * @param {Object} config - AWS configuration object
 * @param {string} tableName - The name of the DynamoDB table
 * @param {Object} key - The key of the item to update
 * @param {string} listName - The name of the list attribute
 * @param {Array} values - The values to append to the list
 * @returns {Promise<Object>} - The response from DynamoDB
 */
async function appendToList(
  config,
  tableName,
  key,
  listName,
  values
) {
  // Initialize the DynamoDB client
  const client = new DynamoDBClient(config);
  const docClient = DynamoDBDocumentClient.from(client);
  
  // Define the update parameters using list_append
  const params = {
    TableName: tableName,
    Key: key,
    UpdateExpression: `SET ${listName} = list_append(if_not_exists(${listName}, :empty_list), :values)`,
    ExpressionAttributeValues: {
      ":empty_list": [],
      ":values": values
    },
    ReturnValues: "UPDATED_NEW"
  };
  
  // Perform the update operation
  const response = await docClient.send(new UpdateCommand(params));
  
  return response;
}

/**
 * Prepend elements to a list attribute.
 * 
 * This function demonstrates how to use the list_append function to add elements
 * to the beginning of a list.
 * 
 * @param {Object} config - AWS configuration object
 * @param {string} tableName - The name of the DynamoDB table
 * @param {Object} key - The key of the item to update
 * @param {string} listName - The name of the list attribute
 * @param {Array} values - The values to prepend to the list
 * @returns {Promise<Object>} - The response from DynamoDB
 */
async function prependToList(
  config,
  tableName,
  key,
  listName,
  values
) {
  // Initialize the DynamoDB client
  const client = new DynamoDBClient(config);
  const docClient = DynamoDBDocumentClient.from(client);
  
  // Define the update parameters using list_append
  // Note: To prepend, we put the new values first in the list_append function
  const params = {
    TableName: tableName,
    Key: key,
    UpdateExpression: `SET ${listName} = list_append(:values, if_not_exists(${listName}, :empty_list))`,
    ExpressionAttributeValues: {
      ":empty_list": [],
      ":values": values
    },
    ReturnValues: "UPDATED_NEW"
  };
  
  // Perform the update operation
  const response = await docClient.send(new UpdateCommand(params));
  
  return response;
}

/**
 * Update a specific element in a list by index.
 * 
 * This function demonstrates how to update a specific element in a list
 * using the index notation.
 * 
 * @param {Object} config - AWS configuration object
 * @param {string} tableName - The name of the DynamoDB table
 * @param {Object} key - The key of the item to update
 * @param {string} listName - The name of the list attribute
 * @param {number} index - The index of the element to update
 * @param {any} value - The new value for the element
 * @returns {Promise<Object>} - The response from DynamoDB
 */
async function updateListElement(
  config,
  tableName,
  key,
  listName,
  index,
  value
) {
  // Initialize the DynamoDB client
  const client = new DynamoDBClient(config);
  const docClient = DynamoDBDocumentClient.from(client);
  
  // Define the update parameters using index notation
  const params = {
    TableName: tableName,
    Key: key,
    UpdateExpression: `SET ${listName}[${index}] = :value`,
    ExpressionAttributeValues: {
      ":value": value
    },
    ReturnValues: "UPDATED_NEW"
  };
  
  // Perform the update operation
  const response = await docClient.send(new UpdateCommand(params));
  
  return response;
}

/**
 * Remove an element from a list by index.
 * 
 * This function demonstrates how to remove a specific element from a list
 * using the REMOVE action with index notation.
 * 
 * @param {Object} config - AWS configuration object
 * @param {string} tableName - The name of the DynamoDB table
 * @param {Object} key - The key of the item to update
 * @param {string} listName - The name of the list attribute
 * @param {number} index - The index of the element to remove
 * @returns {Promise<Object>} - The response from DynamoDB
 */
async function removeListElement(
  config,
  tableName,
  key,
  listName,
  index
) {
  // Initialize the DynamoDB client
  const client = new DynamoDBClient(config);
  const docClient = DynamoDBDocumentClient.from(client);
  
  // Define the update parameters using REMOVE with index notation
  const params = {
    TableName: tableName,
    Key: key,
    UpdateExpression: `REMOVE ${listName}[${index}]`,
    ReturnValues: "UPDATED_NEW"
  };
  
  // Perform the update operation
  const response = await docClient.send(new UpdateCommand(params));
  
  return response;
}

/**
 * Concatenate two lists.
 * 
 * This function demonstrates how to concatenate two lists using the list_append function.
 * 
 * @param {Object} config - AWS configuration object
 * @param {string} tableName - The name of the DynamoDB table
 * @param {Object} key - The key of the item to update
 * @param {string} listName1 - The name of the first list attribute
 * @param {string} listName2 - The name of the second list attribute
 * @param {string} resultListName - The name of the attribute to store the concatenated list
 * @returns {Promise<Object>} - The response from DynamoDB
 */
async function concatenateLists(
  config,
  tableName,
  key,
  listName1,
  listName2,
  resultListName
) {
  // Initialize the DynamoDB client
  const client = new DynamoDBClient(config);
  const docClient = DynamoDBDocumentClient.from(client);
  
  // Define the update parameters using list_append
  const params = {
    TableName: tableName,
    Key: key,
    UpdateExpression: `SET ${resultListName} = list_append(if_not_exists(${listName1}, :empty_list), if_not_exists(${listName2}, :empty_list))`,
    ExpressionAttributeValues: {
      ":empty_list": []
    },
    ReturnValues: "UPDATED_NEW"
  };
  
  // Perform the update operation
  const response = await docClient.send(new UpdateCommand(params));
  
  return response;
}

/**
 * Create a nested list structure.
 * 
 * This function demonstrates how to create and work with nested lists.
 * 
 * @param {Object} config - AWS configuration object
 * @param {string} tableName - The name of the DynamoDB table
 * @param {Object} key - The key of the item to update
 * @param {string} listName - The name of the list attribute
 * @param {Array} nestedLists - An array of arrays to create a nested list structure
 * @returns {Promise<Object>} - The response from DynamoDB
 */
async function createNestedList(
  config,
  tableName,
  key,
  listName,
  nestedLists
) {
  // Initialize the DynamoDB client
  const client = new DynamoDBClient(config);
  const docClient = DynamoDBDocumentClient.from(client);
  
  // Define the update parameters to create a nested list
  const params = {
    TableName: tableName,
    Key: key,
    UpdateExpression: `SET ${listName} = :nested_lists`,
    ExpressionAttributeValues: {
      ":nested_lists": nestedLists
    },
    ReturnValues: "UPDATED_NEW"
  };
  
  // Perform the update operation
  const response = await docClient.send(new UpdateCommand(params));
  
  return response;
}

/**
 * Update an element in a nested list.
 * 
 * This function demonstrates how to update an element in a nested list
 * using multiple index notations.
 * 
 * @param {Object} config - AWS configuration object
 * @param {string} tableName - The name of the DynamoDB table
 * @param {Object} key - The key of the item to update
 * @param {string} listName - The name of the list attribute
 * @param {number} outerIndex - The index in the outer list
 * @param {number} innerIndex - The index in the inner list
 * @param {any} value - The new value for the element
 * @returns {Promise<Object>} - The response from DynamoDB
 */
async function updateNestedListElement(
  config,
  tableName,
  key,
  listName,
  outerIndex,
  innerIndex,
  value
) {
  // Initialize the DynamoDB client
  const client = new DynamoDBClient(config);
  const docClient = DynamoDBDocumentClient.from(client);
  
  // Define the update parameters using multiple index notations
  const params = {
    TableName: tableName,
    Key: key,
    UpdateExpression: `SET ${listName}[${outerIndex}][${innerIndex}] = :value`,
    ExpressionAttributeValues: {
      ":value": value
    },
    ReturnValues: "UPDATED_NEW"
  };
  
  // Perform the update operation
  const response = await docClient.send(new UpdateCommand(params));
  
  return response;
}

/**
 * Get the current value of an item.
 * 
 * Helper function to retrieve the current value of an item.
 * 
 * @param {Object} config - AWS configuration object
 * @param {string} tableName - The name of the DynamoDB table
 * @param {Object} key - The key of the item to get
 * @returns {Promise<Object|null>} - The item or null if not found
 */
async function getItem(
  config,
  tableName,
  key
) {
  // Initialize the DynamoDB client
  const client = new DynamoDBClient(config);
  const docClient = DynamoDBDocumentClient.from(client);
  
  // Define the get parameters
  const params = {
    TableName: tableName,
    Key: key
  };
  
  // Perform the get operation
  const response = await docClient.send(new GetCommand(params));
  
  // Return the item if it exists, otherwise null
  return response.Item || null;
}
```
でのリストオペレーションの使用例 AWS SDK for JavaScript。  

```
/**
 * Example of how to work with lists in DynamoDB.
 */
async function exampleUsage() {
  // Example parameters
  const config = { region: "us-west-2" };
  const tableName = "UserProfiles";
  const key = { UserId: "U12345" };
  
  console.log("Demonstrating list operations in DynamoDB");
  
  try {
    // Example 1: Append elements to a list
    console.log("\nExample 1: Appending elements to a list");
    const response1 = await appendToList(
      config,
      tableName,
      key,
      "RecentSearches",
      ["laptop", "headphones", "monitor"]
    );
    
    console.log("Appended to list:", response1.Attributes);
    
    // Example 2: Prepend elements to a list
    console.log("\nExample 2: Prepending elements to a list");
    const response2 = await prependToList(
      config,
      tableName,
      key,
      "RecentSearches",
      ["keyboard", "mouse"]
    );
    
    console.log("Prepended to list:", response2.Attributes);
    
    // Get the current state of the item
    let currentItem = await getItem(config, tableName, key);
    console.log("\nCurrent state of RecentSearches:", currentItem?.RecentSearches);
    
    // Example 3: Update a specific element in a list
    console.log("\nExample 3: Updating a specific element in a list");
    const response3 = await updateListElement(
      config,
      tableName,
      key,
      "RecentSearches",
      0, // Update the first element
      "mechanical keyboard" // New value
    );
    
    console.log("Updated list element:", response3.Attributes);
    
    // Example 4: Remove an element from a list
    console.log("\nExample 4: Removing an element from a list");
    const response4 = await removeListElement(
      config,
      tableName,
      key,
      "RecentSearches",
      2 // Remove the third element
    );
    
    console.log("List after removing element:", response4.Attributes);
    
    // Example 5: Create and concatenate lists
    console.log("\nExample 5: Creating and concatenating lists");
    
    // First, create two separate lists
    await updateWithMultipleActions(
      config,
      tableName,
      key,
      "SET WishList = :wishlist, SavedItems = :saveditems",
      null,
      {
        ":wishlist": ["gaming laptop", "wireless earbuds"],
        ":saveditems": ["smartphone", "tablet"]
      }
    );
    
    // Then, concatenate them
    const response5 = await concatenateLists(
      config,
      tableName,
      key,
      "WishList",
      "SavedItems",
      "AllItems"
    );
    
    console.log("Concatenated lists:", response5.Attributes);
    
    // Example 6: Create a nested list structure
    console.log("\nExample 6: Creating a nested list structure");
    const response6 = await createNestedList(
      config,
      tableName,
      key,
      "Categories",
      [
        ["Electronics", "Computers", "Accessories"],
        ["Books", "Magazines", "E-books"],
        ["Clothing", "Shoes", "Watches"]
      ]
    );
    
    console.log("Created nested list:", response6.Attributes);
    
    // Example 7: Update an element in a nested list
    console.log("\nExample 7: Updating an element in a nested list");
    const response7 = await updateNestedListElement(
      config,
      tableName,
      key,
      "Categories",
      0, // First inner list
      1, // Second element in that list
      "Laptops" // New value
    );
    
    console.log("Updated nested list element:", response7.Attributes);
    
    // Get the final state of the item
    currentItem = await getItem(config, tableName, key);
    console.log("\nFinal state of the item:", JSON.stringify(currentItem, null, 2));
    
    // Explain list operations
    console.log("\nKey points about list operations in DynamoDB:");
    console.log("1. Use list_append to add elements to a list");
    console.log("2. To append elements, use list_append(existingList, newElements)");
    console.log("3. To prepend elements, use list_append(newElements, existingList)");
    console.log("4. Use if_not_exists to handle cases where the list might not exist yet");
    console.log("5. Use index notation (list[0]) to access or update specific elements");
    console.log("6. Use REMOVE with index notation to remove elements from a list");
    console.log("7. Lists can contain elements of different types");
    console.log("8. Lists can be nested (lists of lists)");
    console.log("9. Use multiple index notations (list[0][1]) to access nested list elements");
    
  } catch (error) {
    console.error("Error:", error);
  }
}

/**
 * Helper function for the examples.
 * 
 * @param {Object} config - AWS configuration object
 * @param {string} tableName - The name of the DynamoDB table
 * @param {Object} key - The key of the item to update
 * @param {string} updateExpression - The update expression
 * @param {Object} expressionAttributeNames - Expression attribute name placeholders
 * @param {Object} expressionAttributeValues - Expression attribute value placeholders
 * @returns {Promise<Object>} - The response from DynamoDB
 */
async function updateWithMultipleActions(
  config,
  tableName,
  key,
  updateExpression,
  expressionAttributeNames,
  expressionAttributeValues
) {
  // Initialize the DynamoDB client
  const client = new DynamoDBClient(config);
  const docClient = DynamoDBDocumentClient.from(client);
  
  // Prepare the update parameters
  const updateParams = {
    TableName: tableName,
    Key: key,
    UpdateExpression: updateExpression,
    ReturnValues: "UPDATED_NEW"
  };
  
  // Add expression attribute names if provided
  if (expressionAttributeNames) {
    updateParams.ExpressionAttributeNames = expressionAttributeNames;
  }
  
  // Add expression attribute values if provided
  if (expressionAttributeValues) {
    updateParams.ExpressionAttributeValues = expressionAttributeValues;
  }
  
  // Execute the update
  const response = await docClient.send(new UpdateCommand(updateParams));
  
  return response;
}
```
+  API の詳細については、*AWS SDK for JavaScript API リファレンス*の「[UpdateItem](https://docs.aws.amazon.com/AWSJavaScriptSDK/v3/latest/client/dynamodb/command/UpdateItemCommand)」を参照してください。

### マップオペレーションを実行する
<a name="dynamodb_Scenario_MapOperations_javascript_topic"></a>

次のコード例は、DynamoDB でマップオペレーションを実行する方法を示しています。
+ マップ構造にネストされた属性を追加および更新します。
+ マップから特定のフィールドを削除します。
+ 深くネストされたマップ属性を操作します。

**SDK for JavaScript (v3)**  
を使用してマップオペレーションをデモンストレーションします AWS SDK for JavaScript。  

```
/**
 * Example of updating map attributes in DynamoDB.
 * 
 * This module demonstrates how to update map attributes that may not exist,
 * how to update nested attributes, and how to handle various map update scenarios.
 */

const { DynamoDBClient } = require("@aws-sdk/client-dynamodb");
const { 
  DynamoDBDocumentClient, 
  UpdateCommand,
  GetCommand
} = require("@aws-sdk/lib-dynamodb");

/**
 * Update a map attribute safely, handling the case where the map might not exist.
 * 
 * This function demonstrates using the if_not_exists function to safely update
 * a map attribute that might not exist yet.
 * 
 * @param {Object} config - AWS configuration object
 * @param {string} tableName - The name of the DynamoDB table
 * @param {Object} key - The key of the item to update
 * @param {string} mapName - The name of the map attribute
 * @param {string} mapKey - The key within the map to update
 * @param {any} value - The value to set
 * @returns {Promise<Object>} - The response from DynamoDB
 */
async function updateMapAttributeSafe(
  config,
  tableName,
  key,
  mapName,
  mapKey,
  value
) {
  // Initialize the DynamoDB client
  const client = new DynamoDBClient(config);
  const docClient = DynamoDBDocumentClient.from(client);
  
  // Define the update parameters using SET with if_not_exists
  const params = {
    TableName: tableName,
    Key: key,
    UpdateExpression: `SET ${mapName}.${mapKey} = :value`,
    ExpressionAttributeValues: {
      ":value": value
    },
    ReturnValues: "UPDATED_NEW"
  };
  
  try {
    // Perform the update operation
    const response = await docClient.send(new UpdateCommand(params));
    return response;
  } catch (error) {
    // If the error is because the map doesn't exist, create it
    if (error.name === "ValidationException" && 
        error.message.includes("The document path provided in the update expression is invalid")) {
      
      // Create the map with the specified key-value pair
      const createParams = {
        TableName: tableName,
        Key: key,
        UpdateExpression: `SET ${mapName} = :map`,
        ExpressionAttributeValues: {
          ":map": { [mapKey]: value }
        },
        ReturnValues: "UPDATED_NEW"
      };
      
      return await docClient.send(new UpdateCommand(createParams));
    }
    
    // Re-throw other errors
    throw error;
  }
}

/**
 * Update a map attribute using the if_not_exists function.
 * 
 * This function demonstrates a more elegant approach using if_not_exists
 * to handle the case where the map doesn't exist yet.
 * 
 * @param {Object} config - AWS configuration object
 * @param {string} tableName - The name of the DynamoDB table
 * @param {Object} key - The key of the item to update
 * @param {string} mapName - The name of the map attribute
 * @param {string} mapKey - The key within the map to update
 * @param {any} value - The value to set
 * @returns {Promise<Object>} - The response from DynamoDB
 */
async function updateMapAttributeWithIfNotExists(
  config,
  tableName,
  key,
  mapName,
  mapKey,
  value
) {
  // Initialize the DynamoDB client
  const client = new DynamoDBClient(config);
  const docClient = DynamoDBDocumentClient.from(client);
  
  // Define the update parameters using SET with if_not_exists
  const params = {
    TableName: tableName,
    Key: key,
    UpdateExpression: `SET ${mapName} = if_not_exists(${mapName}, :emptyMap), ${mapName}.${mapKey} = :value`,
    ExpressionAttributeValues: {
      ":emptyMap": {},
      ":value": value
    },
    ReturnValues: "UPDATED_NEW"
  };
  
  // Perform the update operation
  const response = await docClient.send(new UpdateCommand(params));
  
  return response;
}

/**
 * Add a value to a deeply nested map, creating parent maps if they don't exist.
 * 
 * This function demonstrates how to update a deeply nested attribute,
 * creating any parent maps that don't exist along the way.
 * 
 * @param {Object} config - AWS configuration object
 * @param {string} tableName - The name of the DynamoDB table
 * @param {Object} key - The key of the item to update
 * @param {string[]} path - The path to the nested attribute as an array of keys
 * @param {any} value - The value to set
 * @returns {Promise<Object>} - The response from DynamoDB
 */
async function addToNestedMap(
  config,
  tableName,
  key,
  path,
  value
) {
  // Initialize the DynamoDB client
  const client = new DynamoDBClient(config);
  const docClient = DynamoDBDocumentClient.from(client);
  
  // Build the update expression and expression attribute values
  let updateExpression = "SET";
  const expressionAttributeValues = {};
  
  // For each level in the path, create a map if it doesn't exist
  for (let i = 0; i < path.length; i++) {
    const currentPath = path.slice(0, i + 1).join(".");
    const parentPath = i > 0 ? path.slice(0, i).join(".") : null;
    
    if (parentPath) {
      updateExpression += ` ${parentPath} = if_not_exists(${parentPath}, :emptyMap${i}),`;
      expressionAttributeValues[`:emptyMap${i}`] = {};
    }
  }
  
  // Set the final value
  const fullPath = path.join(".");
  updateExpression += ` ${fullPath} = :value`;
  expressionAttributeValues[":value"] = value;
  
  // Define the update parameters
  const params = {
    TableName: tableName,
    Key: key,
    UpdateExpression: updateExpression,
    ExpressionAttributeValues: expressionAttributeValues,
    ReturnValues: "UPDATED_NEW"
  };
  
  // Perform the update operation
  const response = await docClient.send(new UpdateCommand(params));
  
  return response;
}

/**
 * Update multiple fields in a map attribute in a single operation.
 * 
 * This function demonstrates how to update multiple fields in a map
 * in a single DynamoDB operation.
 * 
 * @param {Object} config - AWS configuration object
 * @param {string} tableName - The name of the DynamoDB table
 * @param {Object} key - The key of the item to update
 * @param {string} mapName - The name of the map attribute
 * @param {Object} updates - Object containing key-value pairs to update
 * @returns {Promise<Object>} - The response from DynamoDB
 */
async function updateMultipleMapFields(
  config,
  tableName,
  key,
  mapName,
  updates
) {
  // Initialize the DynamoDB client
  const client = new DynamoDBClient(config);
  const docClient = DynamoDBDocumentClient.from(client);
  
  // Build the update expression and expression attribute values
  let updateExpression = `SET ${mapName} = if_not_exists(${mapName}, :emptyMap)`;
  const expressionAttributeValues = {
    ":emptyMap": {}
  };
  
  // Add each update to the expression
  Object.entries(updates).forEach(([field, value], index) => {
    updateExpression += `, ${mapName}.${field} = :val${index}`;
    expressionAttributeValues[`:val${index}`] = value;
  });
  
  // Define the update parameters
  const params = {
    TableName: tableName,
    Key: key,
    UpdateExpression: updateExpression,
    ExpressionAttributeValues: expressionAttributeValues,
    ReturnValues: "UPDATED_NEW"
  };
  
  // Perform the update operation
  const response = await docClient.send(new UpdateCommand(params));
  
  return response;
}

/**
 * Get the current value of an item.
 * 
 * Helper function to retrieve the current value of an item.
 * 
 * @param {Object} config - AWS configuration object
 * @param {string} tableName - The name of the DynamoDB table
 * @param {Object} key - The key of the item to get
 * @returns {Promise<Object|null>} - The item or null if not found
 */
async function getItem(
  config,
  tableName,
  key
) {
  // Initialize the DynamoDB client
  const client = new DynamoDBClient(config);
  const docClient = DynamoDBDocumentClient.from(client);
  
  // Define the get parameters
  const params = {
    TableName: tableName,
    Key: key
  };
  
  // Perform the get operation
  const response = await docClient.send(new GetCommand(params));
  
  // Return the item if it exists, otherwise null
  return response.Item || null;
}

/**
 * Example of how to use the map attribute update functions.
 */
async function exampleUsage() {
  // Example parameters
  const config = { region: "us-west-2" };
  const tableName = "Users";
  const key = { UserId: "U12345" };
  
  console.log("Demonstrating different approaches to update map attributes in DynamoDB");
  
  try {
    // Example 1: Update a map attribute that might not exist (two-step approach)
    console.log("\nExample 1: Updating a map attribute that might not exist (two-step approach)");
    const response1 = await updateMapAttributeSafe(
      config,
      tableName,
      key,
      "Preferences",
      "Theme",
      "Dark"
    );
    
    console.log("Updated preferences:", response1.Attributes);
    
    // Example 2: Update a map attribute using if_not_exists (elegant approach)
    console.log("\nExample 2: Updating a map attribute using if_not_exists (elegant approach)");
    const response2 = await updateMapAttributeWithIfNotExists(
      config,
      tableName,
      key,
      "Settings",
      "NotificationsEnabled",
      true
    );
    
    console.log("Updated settings:", response2.Attributes);
    
    // Example 3: Update a deeply nested attribute
    console.log("\nExample 3: Updating a deeply nested attribute");
    const response3 = await addToNestedMap(
      config,
      tableName,
      key,
      ["Profile", "Address", "City"],
      "Seattle"
    );
    
    console.log("Updated nested attribute:", response3.Attributes);
    
    // Example 4: Update multiple fields in a map
    console.log("\nExample 4: Updating multiple fields in a map");
    const response4 = await updateMultipleMapFields(
      config,
      tableName,
      key,
      "ContactInfo",
      {
        Email: "user@example.com",
        Phone: "555-123-4567",
        PreferredContact: "Email"
      }
    );
    
    console.log("Updated multiple fields:", response4.Attributes);
    
    // Get the final state of the item
    console.log("\nFinal state of the item:");
    const item = await getItem(config, tableName, key);
    console.log(JSON.stringify(item, null, 2));
    
    // Explain the benefits of different approaches
    console.log("\nKey points about updating map attributes:");
    console.log("1. Use if_not_exists to handle maps that might not exist");
    console.log("2. Multiple updates can be combined in a single operation");
    console.log("3. Deeply nested attributes require creating parent maps");
    console.log("4. DynamoDB expressions are atomic - the entire update succeeds or fails");
    console.log("5. Using a single operation is more efficient than multiple separate updates");
    
  } catch (error) {
    console.error("Error:", error);
  }
}

// Export the functions
module.exports = {
  updateMapAttributeSafe,
  updateMapAttributeWithIfNotExists,
  addToNestedMap,
  updateMultipleMapFields,
  getItem,
  exampleUsage
};

// Run the example if this file is executed directly
if (require.main === module) {
  exampleUsage();
}
```
+  API の詳細については、*AWS SDK for JavaScript API リファレンス*の「[UpdateItem](https://docs.aws.amazon.com/AWSJavaScriptSDK/v3/latest/client/dynamodb/command/UpdateItemCommand)」を参照してください。

### セットオペレーションを実行する
<a name="dynamodb_Scenario_SetOperations_javascript_topic"></a>

次のコード例は、DynamoDB でセットオペレーションを実行する方法を示しています。
+ セット属性に要素を追加します。
+ セット属性から要素を削除します。
+ セットで ADD および DELETE オペレーションを使用します。

**SDK for JavaScript (v3)**  
を使用してセットオペレーションをデモンストレーションします AWS SDK for JavaScript。  

```
const { DynamoDBClient } = require("@aws-sdk/client-dynamodb");
const { 
  DynamoDBDocumentClient, 
  UpdateCommand,
  GetCommand
} = require("@aws-sdk/lib-dynamodb");

/**
 * Add elements to a set attribute.
 * 
 * This function demonstrates using the ADD operation to add elements to a set.
 * 
 * @param {Object} config - AWS configuration object
 * @param {string} tableName - The name of the DynamoDB table
 * @param {Object} key - The key of the item to update
 * @param {string} setName - The name of the set attribute
 * @param {Array} values - The values to add to the set
 * @param {string} setType - The type of set ('string', 'number', or 'binary')
 * @returns {Promise<Object>} - The response from DynamoDB
 */
async function addToSet(
  config,
  tableName,
  key,
  setName,
  values,
  setType = 'string'
) {
  // Initialize the DynamoDB client
  const client = new DynamoDBClient(config);
  const docClient = DynamoDBDocumentClient.from(client);
  
  // Create the appropriate set type
  let setValues;
  if (setType === 'string') {
    setValues = new Set(values.map(String));
  } else if (setType === 'number') {
    setValues = new Set(values.map(Number));
  } else if (setType === 'binary') {
    setValues = new Set(values);
  } else {
    throw new Error(`Unsupported set type: ${setType}`);
  }
  
  // Define the update parameters using ADD
  const params = {
    TableName: tableName,
    Key: key,
    UpdateExpression: `ADD ${setName} :values`,
    ExpressionAttributeValues: {
      ":values": setValues
    },
    ReturnValues: "UPDATED_NEW"
  };
  
  // Perform the update operation
  const response = await docClient.send(new UpdateCommand(params));
  
  return response;
}

/**
 * Remove elements from a set attribute.
 * 
 * This function demonstrates using the DELETE operation to remove elements from a set.
 * 
 * @param {Object} config - AWS configuration object
 * @param {string} tableName - The name of the DynamoDB table
 * @param {Object} key - The key of the item to update
 * @param {string} setName - The name of the set attribute
 * @param {Array} values - The values to remove from the set
 * @param {string} setType - The type of set ('string', 'number', or 'binary')
 * @returns {Promise<Object>} - The response from DynamoDB
 */
async function removeFromSet(
  config,
  tableName,
  key,
  setName,
  values,
  setType = 'string'
) {
  // Initialize the DynamoDB client
  const client = new DynamoDBClient(config);
  const docClient = DynamoDBDocumentClient.from(client);
  
  // Create the appropriate set type
  let setValues;
  if (setType === 'string') {
    setValues = new Set(values.map(String));
  } else if (setType === 'number') {
    setValues = new Set(values.map(Number));
  } else if (setType === 'binary') {
    setValues = new Set(values);
  } else {
    throw new Error(`Unsupported set type: ${setType}`);
  }
  
  // Define the update parameters using DELETE
  const params = {
    TableName: tableName,
    Key: key,
    UpdateExpression: `DELETE ${setName} :values`,
    ExpressionAttributeValues: {
      ":values": setValues
    },
    ReturnValues: "UPDATED_NEW"
  };
  
  // Perform the update operation
  const response = await docClient.send(new UpdateCommand(params));
  
  return response;
}

/**
 * Create a new set attribute with initial values.
 * 
 * This function demonstrates using the SET operation to create a new set attribute.
 * 
 * @param {Object} config - AWS configuration object
 * @param {string} tableName - The name of the DynamoDB table
 * @param {Object} key - The key of the item to update
 * @param {string} setName - The name of the set attribute
 * @param {Array} values - The initial values for the set
 * @param {string} setType - The type of set ('string', 'number', or 'binary')
 * @returns {Promise<Object>} - The response from DynamoDB
 */
async function createSet(
  config,
  tableName,
  key,
  setName,
  values,
  setType = 'string'
) {
  // Initialize the DynamoDB client
  const client = new DynamoDBClient(config);
  const docClient = DynamoDBDocumentClient.from(client);
  
  // Create the appropriate set type
  let setValues;
  if (setType === 'string') {
    setValues = new Set(values.map(String));
  } else if (setType === 'number') {
    setValues = new Set(values.map(Number));
  } else if (setType === 'binary') {
    setValues = new Set(values);
  } else {
    throw new Error(`Unsupported set type: ${setType}`);
  }
  
  // Define the update parameters using SET
  const params = {
    TableName: tableName,
    Key: key,
    UpdateExpression: `SET ${setName} = :values`,
    ExpressionAttributeValues: {
      ":values": setValues
    },
    ReturnValues: "UPDATED_NEW"
  };
  
  // Perform the update operation
  const response = await docClient.send(new UpdateCommand(params));
  
  return response;
}

/**
 * Replace an entire set attribute with a new set of values.
 * 
 * This function demonstrates using the SET operation to replace an entire set.
 * 
 * @param {Object} config - AWS configuration object
 * @param {string} tableName - The name of the DynamoDB table
 * @param {Object} key - The key of the item to update
 * @param {string} setName - The name of the set attribute
 * @param {Array} values - The new values for the set
 * @param {string} setType - The type of set ('string', 'number', or 'binary')
 * @returns {Promise<Object>} - The response from DynamoDB
 */
async function replaceSet(
  config,
  tableName,
  key,
  setName,
  values,
  setType = 'string'
) {
  // This is the same as createSet, but included for clarity of intent
  return await createSet(config, tableName, key, setName, values, setType);
}

/**
 * Remove the last element from a set and handle the empty set case.
 * 
 * This function demonstrates what happens when you delete the last element of a set.
 * 
 * @param {Object} config - AWS configuration object
 * @param {string} tableName - The name of the DynamoDB table
 * @param {Object} key - The key of the item to update
 * @param {string} setName - The name of the set attribute
 * @returns {Promise<Object>} - The result of the operation
 */
async function removeLastElementFromSet(
  config,
  tableName,
  key,
  setName
) {
  // Initialize the DynamoDB client
  const client = new DynamoDBClient(config);
  const docClient = DynamoDBDocumentClient.from(client);
  
  // First, get the current item to check the set
  const currentItem = await getItem(config, tableName, key);
  
  // Check if the set exists and has elements
  if (!currentItem || !currentItem[setName] || currentItem[setName].size === 0) {
    return {
      success: false,
      message: "Set doesn't exist or is already empty",
      item: currentItem
    };
  }
  
  // Get the set values
  const setValues = Array.from(currentItem[setName]);
  
  // If there's only one element left, remove the attribute entirely
  if (setValues.length === 1) {
    // Define the update parameters to remove the attribute
    const params = {
      TableName: tableName,
      Key: key,
      UpdateExpression: `REMOVE ${setName}`,
      ReturnValues: "UPDATED_NEW"
    };
    
    // Perform the update operation
    await docClient.send(new UpdateCommand(params));
    
    return {
      success: true,
      message: "Last element removed, attribute has been deleted",
      removedValue: setValues[0]
    };
  } else {
    // Otherwise, remove just the last element
    // Create a set with just the last element
    const lastElement = setValues[setValues.length - 1];
    const setType = typeof lastElement === 'number' ? 'number' : 'string';
    
    // Remove the last element
    const response = await removeFromSet(
      config,
      tableName,
      key,
      setName,
      [lastElement],
      setType
    );
    
    return {
      success: true,
      message: "Last element removed, set still contains elements",
      removedValue: lastElement,
      remainingSet: response.Attributes[setName]
    };
  }
}

/**
 * Get the current value of an item.
 * 
 * Helper function to retrieve the current value of an item.
 * 
 * @param {Object} config - AWS configuration object
 * @param {string} tableName - The name of the DynamoDB table
 * @param {Object} key - The key of the item to get
 * @returns {Promise<Object|null>} - The item or null if not found
 */
async function getItem(
  config,
  tableName,
  key
) {
  // Initialize the DynamoDB client
  const client = new DynamoDBClient(config);
  const docClient = DynamoDBDocumentClient.from(client);
  
  // Define the get parameters
  const params = {
    TableName: tableName,
    Key: key
  };
  
  // Perform the get operation
  const response = await docClient.send(new GetCommand(params));
  
  // Return the item if it exists, otherwise null
  return response.Item || null;
}
```
でのセットオペレーションの使用例 AWS SDK for JavaScript。  

```
/**
 * Example of how to work with sets in DynamoDB.
 */
async function exampleUsage() {
  // Example parameters
  const config = { region: "us-west-2" };
  const tableName = "Users";
  const key = { UserId: "U12345" };
  
  console.log("Demonstrating set operations in DynamoDB");
  
  try {
    // Example 1: Create a string set
    console.log("\nExample 1: Creating a string set");
    const response1 = await createSet(
      config,
      tableName,
      key,
      "Interests",
      ["Reading", "Hiking", "Cooking"],
      "string"
    );
    
    console.log("Created set:", response1.Attributes);
    
    // Example 2: Add elements to a set
    console.log("\nExample 2: Adding elements to a set");
    const response2 = await addToSet(
      config,
      tableName,
      key,
      "Interests",
      ["Photography", "Travel"],
      "string"
    );
    
    console.log("Updated set after adding elements:", response2.Attributes);
    
    // Example 3: Remove elements from a set
    console.log("\nExample 3: Removing elements from a set");
    const response3 = await removeFromSet(
      config,
      tableName,
      key,
      "Interests",
      ["Cooking"],
      "string"
    );
    
    console.log("Updated set after removing elements:", response3.Attributes);
    
    // Example 4: Create a number set
    console.log("\nExample 4: Creating a number set");
    const response4 = await createSet(
      config,
      tableName,
      key,
      "FavoriteNumbers",
      [7, 42, 99],
      "number"
    );
    
    console.log("Created number set:", response4.Attributes);
    
    // Example 5: Replace an entire set
    console.log("\nExample 5: Replacing an entire set");
    const response5 = await replaceSet(
      config,
      tableName,
      key,
      "Interests",
      ["Gaming", "Movies", "Music"],
      "string"
    );
    
    console.log("Replaced set:", response5.Attributes);
    
    // Example 6: Remove the last element from a set
    console.log("\nExample 6: Removing the last element from a set");
    
    // First, create a set with just one element
    await createSet(
      config,
      tableName,
      { UserId: "U67890" },
      "Tags",
      ["LastTag"],
      "string"
    );
    
    // Then, remove the last element
    const response6 = await removeLastElementFromSet(
      config,
      tableName,
      { UserId: "U67890" },
      "Tags"
    );
    
    console.log(response6.message);
    console.log("Removed value:", response6.removedValue);
    
    // Get the final state of the items
    console.log("\nFinal state of the items:");
    const item1 = await getItem(config, tableName, key);
    console.log("User U12345:", JSON.stringify(item1, null, 2));
    
    const item2 = await getItem(config, tableName, { UserId: "U67890" });
    console.log("User U67890:", JSON.stringify(item2, null, 2));
    
    // Explain set operations
    console.log("\nKey points about set operations in DynamoDB:");
    console.log("1. Use ADD to add elements to a set (duplicates are automatically removed)");
    console.log("2. Use DELETE to remove elements from a set");
    console.log("3. Use SET to create a new set or replace an existing one");
    console.log("4. DynamoDB supports three types of sets: string sets, number sets, and binary sets");
    console.log("5. When you delete the last element from a set, the attribute remains as an empty set");
    console.log("6. To remove an empty set, use the REMOVE operation");
    console.log("7. Sets automatically maintain unique values (no duplicates)");
    console.log("8. You cannot mix data types within a set");
    
  } catch (error) {
    console.error("Error:", error);
  }
}
```
+  API の詳細については、*AWS SDK for JavaScript API リファレンス*の[UpdateItem](https://docs.aws.amazon.com/AWSJavaScriptSDK/v3/latest/client/dynamodb/command/UpdateItemCommand)」を参照してください。

### PartiQL ステートメントのバッチを使用してテーブルに対してクエリを実行する
<a name="dynamodb_Scenario_PartiQLBatch_javascript_topic"></a>

次のコードサンプルは、以下の操作方法を示しています。
+ 複数の SELECT ステートメントを実行して、項目のバッチを取得します。
+ 複数の INSERT ステートメントを実行して、項目のバッチを追加する。
+ 複数の UPDATE ステートメントを実行して、項目のバッチを更新する。
+ 複数の DELETE ステートメントを実行して、項目のバッチを削除します。

**SDK for JavaScript (v3)**  
 GitHub には、その他のリソースもあります。用例一覧を検索し、[AWS コード例リポジトリ](https://github.com/awsdocs/aws-doc-sdk-examples/tree/main/javascriptv3/example_code/dynamodb#code-examples)での設定と実行の方法を確認してください。
PartiQL ステートメントのバッチを実行します。  

```
import {
  BillingMode,
  CreateTableCommand,
  DeleteTableCommand,
  DescribeTableCommand,
  DynamoDBClient,
  waitUntilTableExists,
} from "@aws-sdk/client-dynamodb";
import {
  DynamoDBDocumentClient,
  BatchExecuteStatementCommand,
} from "@aws-sdk/lib-dynamodb";
import { ScenarioInput } from "@aws-doc-sdk-examples/lib/scenario";

const client = new DynamoDBClient({});
const docClient = DynamoDBDocumentClient.from(client);

const log = (msg) => console.log(`[SCENARIO] ${msg}`);
const tableName = "Cities";

export const main = async (confirmAll = false) => {
  /**
   * Delete table if it exists.
   */
  try {
    await client.send(new DescribeTableCommand({ TableName: tableName }));
    // If no error was thrown, the table exists.
    const input = new ScenarioInput(
      "deleteTable",
      `A table named ${tableName} already exists. If you choose not to delete
this table, the scenario cannot continue. Delete it?`,
      { type: "confirm", confirmAll },
    );
    const deleteTable = await input.handle({}, { confirmAll });
    if (deleteTable) {
      await client.send(new DeleteTableCommand({ tableName }));
    } else {
      console.warn(
        "Scenario could not run. Either delete ${tableName} or provide a unique table name.",
      );
      return;
    }
  } catch (caught) {
    if (
      caught instanceof Error &&
      caught.name === "ResourceNotFoundException"
    ) {
      // Do nothing. This means the table is not there.
    } else {
      throw caught;
    }
  }

  /**
   * Create a table.
   */

  log("Creating a table.");
  const createTableCommand = new CreateTableCommand({
    TableName: tableName,
    // This example performs a large write to the database.
    // Set the billing mode to PAY_PER_REQUEST to
    // avoid throttling the large write.
    BillingMode: BillingMode.PAY_PER_REQUEST,
    // Define the attributes that are necessary for the key schema.
    AttributeDefinitions: [
      {
        AttributeName: "name",
        // 'S' is a data type descriptor that represents a number type.
        // For a list of all data type descriptors, see the following link.
        // https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/Programming.LowLevelAPI.html#Programming.LowLevelAPI.DataTypeDescriptors
        AttributeType: "S",
      },
    ],
    // The KeySchema defines the primary key. The primary key can be
    // a partition key, or a combination of a partition key and a sort key.
    // Key schema design is important. For more info, see
    // https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/best-practices.html
    KeySchema: [{ AttributeName: "name", KeyType: "HASH" }],
  });
  await client.send(createTableCommand);
  log(`Table created: ${tableName}.`);

  /**
   * Wait until the table is active.
   */

  // This polls with DescribeTableCommand until the requested table is 'ACTIVE'.
  // You can't write to a table before it's active.
  log("Waiting for the table to be active.");
  await waitUntilTableExists({ client }, { TableName: tableName });
  log("Table active.");

  /**
   * Insert items.
   */

  log("Inserting cities into the table.");
  const addItemsStatementCommand = new BatchExecuteStatementCommand({
    // https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/ql-reference.insert.html
    Statements: [
      {
        Statement: `INSERT INTO ${tableName} value {'name':?, 'population':?}`,
        Parameters: ["Alachua", 10712],
      },
      {
        Statement: `INSERT INTO ${tableName} value {'name':?, 'population':?}`,
        Parameters: ["High Springs", 6415],
      },
    ],
  });
  await docClient.send(addItemsStatementCommand);
  log("Cities inserted.");

  /**
   * Select items.
   */

  log("Selecting cities from the table.");
  const selectItemsStatementCommand = new BatchExecuteStatementCommand({
    // https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/ql-reference.select.html
    Statements: [
      {
        Statement: `SELECT * FROM ${tableName} WHERE name=?`,
        Parameters: ["Alachua"],
      },
      {
        Statement: `SELECT * FROM ${tableName} WHERE name=?`,
        Parameters: ["High Springs"],
      },
    ],
  });
  const selectItemResponse = await docClient.send(selectItemsStatementCommand);
  log(
    `Got cities: ${selectItemResponse.Responses.map(
      (r) => `${r.Item.name} (${r.Item.population})`,
    ).join(", ")}`,
  );

  /**
   * Update items.
   */

  log("Modifying the populations.");
  const updateItemStatementCommand = new BatchExecuteStatementCommand({
    // https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/ql-reference.update.html
    Statements: [
      {
        Statement: `UPDATE ${tableName} SET population=? WHERE name=?`,
        Parameters: [10, "Alachua"],
      },
      {
        Statement: `UPDATE ${tableName} SET population=? WHERE name=?`,
        Parameters: [5, "High Springs"],
      },
    ],
  });
  await docClient.send(updateItemStatementCommand);
  log("Updated cities.");

  /**
   * Delete the items.
   */

  log("Deleting the cities.");
  const deleteItemStatementCommand = new BatchExecuteStatementCommand({
    // https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/ql-reference.delete.html
    Statements: [
      {
        Statement: `DELETE FROM ${tableName} WHERE name=?`,
        Parameters: ["Alachua"],
      },
      {
        Statement: `DELETE FROM ${tableName} WHERE name=?`,
        Parameters: ["High Springs"],
      },
    ],
  });
  await docClient.send(deleteItemStatementCommand);
  log("Cities deleted.");

  /**
   * Delete the table.
   */

  log("Deleting the table.");
  const deleteTableCommand = new DeleteTableCommand({ TableName: tableName });
  await client.send(deleteTableCommand);
  log("Table deleted.");
};
```
+  API の詳細については、*AWS SDK for JavaScript API リファレンス*の「[BatchExecuteStatement](https://docs.aws.amazon.com/AWSJavaScriptSDK/v3/latest/client/dynamodb/command/BatchExecuteStatementCommand)」を参照してください。

### PartiQL を使用してテーブルに対してクエリを実行する
<a name="dynamodb_Scenario_PartiQLSingle_javascript_topic"></a>

次のコードサンプルは、以下の操作方法を示しています。
+ SELECT ステートメントを実行して項目を取得します。
+ INSERT 文を実行して項目を追加する。
+ UPDATE ステートメントを使用して項目を更新する。
+ DELETE ステートメントを実行して項目を削除します。

**SDK for JavaScript (v3)**  
 GitHub には、その他のリソースもあります。用例一覧を検索し、[AWS コード例リポジトリ](https://github.com/awsdocs/aws-doc-sdk-examples/tree/main/javascriptv3/example_code/dynamodb#code-examples)での設定と実行の方法を確認してください。
単一の PartiQL ステートメントを実行します。  

```
import {
  BillingMode,
  CreateTableCommand,
  DeleteTableCommand,
  DescribeTableCommand,
  DynamoDBClient,
  waitUntilTableExists,
} from "@aws-sdk/client-dynamodb";
import {
  DynamoDBDocumentClient,
  ExecuteStatementCommand,
} from "@aws-sdk/lib-dynamodb";
import { ScenarioInput } from "@aws-doc-sdk-examples/lib/scenario";

const client = new DynamoDBClient({});
const docClient = DynamoDBDocumentClient.from(client);

const log = (msg) => console.log(`[SCENARIO] ${msg}`);
const tableName = "SingleOriginCoffees";

export const main = async (confirmAll = false) => {
  /**
   * Delete table if it exists.
   */
  try {
    await client.send(new DescribeTableCommand({ TableName: tableName }));
    // If no error was thrown, the table exists.
    const input = new ScenarioInput(
      "deleteTable",
      `A table named ${tableName} already exists. If you choose not to delete
this table, the scenario cannot continue. Delete it?`,
      { type: "confirm", confirmAll },
    );
    const deleteTable = await input.handle({});
    if (deleteTable) {
      await client.send(new DeleteTableCommand({ tableName }));
    } else {
      console.warn(
        "Scenario could not run. Either delete ${tableName} or provide a unique table name.",
      );
      return;
    }
  } catch (caught) {
    if (
      caught instanceof Error &&
      caught.name === "ResourceNotFoundException"
    ) {
      // Do nothing. This means the table is not there.
    } else {
      throw caught;
    }
  }

  /**
   * Create a table.
   */

  log("Creating a table.");
  const createTableCommand = new CreateTableCommand({
    TableName: tableName,
    // This example performs a large write to the database.
    // Set the billing mode to PAY_PER_REQUEST to
    // avoid throttling the large write.
    BillingMode: BillingMode.PAY_PER_REQUEST,
    // Define the attributes that are necessary for the key schema.
    AttributeDefinitions: [
      {
        AttributeName: "varietal",
        // 'S' is a data type descriptor that represents a number type.
        // For a list of all data type descriptors, see the following link.
        // https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/Programming.LowLevelAPI.html#Programming.LowLevelAPI.DataTypeDescriptors
        AttributeType: "S",
      },
    ],
    // The KeySchema defines the primary key. The primary key can be
    // a partition key, or a combination of a partition key and a sort key.
    // Key schema design is important. For more info, see
    // https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/best-practices.html
    KeySchema: [{ AttributeName: "varietal", KeyType: "HASH" }],
  });
  await client.send(createTableCommand);
  log(`Table created: ${tableName}.`);

  /**
   * Wait until the table is active.
   */

  // This polls with DescribeTableCommand until the requested table is 'ACTIVE'.
  // You can't write to a table before it's active.
  log("Waiting for the table to be active.");
  await waitUntilTableExists({ client }, { TableName: tableName });
  log("Table active.");

  /**
   * Insert an item.
   */

  log("Inserting a coffee into the table.");
  const addItemStatementCommand = new ExecuteStatementCommand({
    // https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/ql-reference.insert.html
    Statement: `INSERT INTO ${tableName} value {'varietal':?, 'profile':?}`,
    Parameters: ["arabica", ["chocolate", "floral"]],
  });
  await client.send(addItemStatementCommand);
  log("Coffee inserted.");

  /**
   * Select an item.
   */

  log("Selecting the coffee from the table.");
  const selectItemStatementCommand = new ExecuteStatementCommand({
    // https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/ql-reference.select.html
    Statement: `SELECT * FROM ${tableName} WHERE varietal=?`,
    Parameters: ["arabica"],
  });
  const selectItemResponse = await docClient.send(selectItemStatementCommand);
  log(`Got coffee: ${JSON.stringify(selectItemResponse.Items[0])}`);

  /**
   * Update the item.
   */

  log("Add a flavor profile to the coffee.");
  const updateItemStatementCommand = new ExecuteStatementCommand({
    // https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/ql-reference.update.html
    Statement: `UPDATE ${tableName} SET profile=list_append(profile, ?) WHERE varietal=?`,
    Parameters: [["fruity"], "arabica"],
  });
  await client.send(updateItemStatementCommand);
  log("Updated coffee");

  /**
   * Delete the item.
   */

  log("Deleting the coffee.");
  const deleteItemStatementCommand = new ExecuteStatementCommand({
    // https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/ql-reference.delete.html
    Statement: `DELETE FROM ${tableName} WHERE varietal=?`,
    Parameters: ["arabica"],
  });
  await docClient.send(deleteItemStatementCommand);
  log("Coffee deleted.");

  /**
   * Delete the table.
   */

  log("Deleting the table.");
  const deleteTableCommand = new DeleteTableCommand({ TableName: tableName });
  await client.send(deleteTableCommand);
  log("Table deleted.");
};
```
+  API の詳細については、*AWS SDK for JavaScript API リファレンス*の「[ExecuteStatement](https://docs.aws.amazon.com/AWSJavaScriptSDK/v3/latest/client/dynamodb/command/ExecuteStatementCommand)」を参照してください。

### グローバルセカンダリインデックスを使用してテーブルをクエリする
<a name="dynamodb_Scenarios_QueryWithGlobalSecondaryIndex_javascript_topic"></a>

以下のコード例は、グローバルセカンダリインデックスを使用してテーブルをクエリする方法を示しています。
+ プライマリキーを使用して DynamoDB テーブルをクエリします。
+ 代替アクセスパターンのグローバルセカンダリインデックス (GSI) をクエリします。
+ テーブルクエリと GSI クエリを比較します。

**SDK for JavaScript (v3)**  
でプライマリキーを使用して DynamoDB テーブルをクエリします AWS SDK for JavaScript。  

```
const { DynamoDBClient, QueryCommand } = require("@aws-sdk/client-dynamodb");

/**
 * Queries a DynamoDB table using the primary key
 * 
 * @param {Object} config - AWS SDK configuration object
 * @param {string} tableName - The name of the DynamoDB table
 * @param {string} userId - The user ID to query by (partition key)
 * @returns {Promise<Object>} - The query response
 */
async function queryTable(
  config,
  tableName,
  userId
) {
  try {
    // Create DynamoDB client
    const client = new DynamoDBClient(config);

    // Construct the query input for the base table
    const input = {
      TableName: tableName,
      KeyConditionExpression: "user_id = :userId",
      ExpressionAttributeValues: {
        ":userId": { S: userId }
      }
    };

    // Execute the query
    const command = new QueryCommand(input);
    return await client.send(command);
  } catch (error) {
    console.error(`Error querying table: ${error}`);
    throw error;
  }
}
```
を使用して DynamoDB グローバルセカンダリインデックス (GSI) をクエリします AWS SDK for JavaScript。  

```
/**
 * Queries a DynamoDB Global Secondary Index (GSI)
 * 
 * @param {Object} config - AWS SDK configuration object
 * @param {string} tableName - The name of the DynamoDB table
 * @param {string} indexName - The name of the GSI to query
 * @param {string} gameId - The game ID to query by (GSI partition key)
 * @returns {Promise<Object>} - The query response
 */
async function queryGSI(
  config,
  tableName,
  indexName,
  gameId
) {
  try {
    // Create DynamoDB client
    const client = new DynamoDBClient(config);

    // Construct the query input for the GSI
    const input = {
      TableName: tableName,
      IndexName: indexName,
      KeyConditionExpression: "game_id = :gameId",
      ExpressionAttributeValues: {
        ":gameId": { S: gameId }
      }
    };

    // Execute the query
    const command = new QueryCommand(input);
    return await client.send(command);
  } catch (error) {
    console.error(`Error querying GSI: ${error}`);
    throw error;
  }
}
```
+  API の詳細については、*AWS SDK for JavaScript API リファレンス*の「[Query](https://docs.aws.amazon.com/AWSJavaScriptSDK/v3/latest/client/dynamodb/command/QueryCommand)」を参照してください。

### begins\$1with 条件を使用してテーブルをクエリする
<a name="dynamodb_Scenarios_QueryWithBeginsWithCondition_javascript_topic"></a>

以下のコード例は、begins\$1with 条件を使用してテーブルをクエリする方法を示しています。
+ キー条件式で begins\$1with 関数を使用します。
+ ソートキーのプレフィックスパターンに基づいて項目をフィルタリングします。

**SDK for JavaScript (v3)**  
 AWS SDK for JavaScriptでソートキーの begins\$1with 条件を使用して DynamoDB テーブルをクエリします。  

```
const { DynamoDBClient, QueryCommand } = require("@aws-sdk/client-dynamodb");

/**
 * Queries a DynamoDB table for items where the sort key begins with a specific prefix
 * 
 * @param {Object} config - AWS SDK configuration object
 * @param {string} tableName - The name of the DynamoDB table
 * @param {string} partitionKeyName - The name of the partition key
 * @param {string} partitionKeyValue - The value of the partition key
 * @param {string} sortKeyName - The name of the sort key
 * @param {string} prefix - The prefix to match at the beginning of the sort key
 * @returns {Promise<Object>} - The query response
 */
async function queryWithBeginsWith(
  config,
  tableName,
  partitionKeyName,
  partitionKeyValue,
  sortKeyName,
  prefix
) {
  try {
    // Create DynamoDB client
    const client = new DynamoDBClient(config);

    // Construct the query input
    const input = {
      TableName: tableName,
      KeyConditionExpression: "#pk = :pkValue AND begins_with(#sk, :prefix)",
      ExpressionAttributeNames: {
        "#pk": partitionKeyName,
        "#sk": sortKeyName
      },
      ExpressionAttributeValues: {
        ":pkValue": { S: partitionKeyValue },
        ":prefix": { S: prefix }
      }
    };

    // Execute the query
    const command = new QueryCommand(input);
    return await client.send(command);
  } catch (error) {
    console.error(`Error querying with begins_with: ${error}`);
    throw error;
  }
}
```
+  API の詳細については、*AWS SDK for JavaScript API リファレンス*の「[Query](https://docs.aws.amazon.com/AWSJavaScriptSDK/v3/latest/client/dynamodb/command/QueryCommand)」を参照してください。

### 日付範囲を使用してテーブルをクエリする
<a name="dynamodb_Scenarios_QueryWithDateRange_javascript_topic"></a>

以下のコード例は、ソートキーの日付範囲を使用してテーブルをクエリする方法を示しています。
+ 特定の日付範囲内の項目をクエリします。
+ 日付形式のソートキーで比較演算子を使用します。

**SDK for JavaScript (v3)**  
を使用して、日付範囲内の項目について DynamoDB テーブルをクエリします AWS SDK for JavaScript。  

```
const { DynamoDBClient, QueryCommand } = require("@aws-sdk/client-dynamodb");

/**
 * Queries a DynamoDB table for items within a specific date range on the sort key
 * 
 * @param {Object} config - AWS SDK configuration object
 * @param {string} tableName - The name of the DynamoDB table
 * @param {string} partitionKeyName - The name of the partition key
 * @param {string} partitionKeyValue - The value of the partition key
 * @param {string} sortKeyName - The name of the sort key (must be a date/time attribute)
 * @param {Date} startDate - The start date for the range query
 * @param {Date} endDate - The end date for the range query
 * @returns {Promise<Object>} - The query response
 */
async function queryByDateRangeOnSortKey(
  config,
  tableName,
  partitionKeyName,
  partitionKeyValue,
  sortKeyName,
  startDate,
  endDate
) {
  try {
    // Create DynamoDB client
    const client = new DynamoDBClient(config);

    // Format dates as ISO strings for DynamoDB
    const formattedStartDate = startDate.toISOString();
    const formattedEndDate = endDate.toISOString();

    // Construct the query input
    const input = {
      TableName: tableName,
      KeyConditionExpression: '#pk = :pkValue AND #sk BETWEEN :startDate AND :endDate',
      ExpressionAttributeNames: {
        "#pk": partitionKeyName,
        "#sk": sortKeyName
      },
      ExpressionAttributeValues: {
        ":pkValue": { S: partitionKeyValue },
        ":startDate": { S: formattedStartDate },
        ":endDate": { S: formattedEndDate }
      }
    };

    // Execute the query
    const command = new QueryCommand(input);
    return await client.send(command);
  } catch (error) {
    console.error(`Error querying by date range on sort key: ${error}`);
    throw error;
  }
}
```
+  API の詳細については、*AWS SDK for JavaScript API リファレンス*の「[Query](https://docs.aws.amazon.com/AWSJavaScriptSDK/v3/latest/client/dynamodb/command/QueryCommand)」を参照してください。

### 複雑なフィルター式を使用してテーブルをクエリする
<a name="dynamodb_Scenarios_QueryWithComplexFilter_javascript_topic"></a>

次のコード例は、複雑なフィルター式を使用してテーブルをクエリする方法を示しています。
+ 複雑なフィルター式をクエリ結果に適用します。
+ 論理演算子を使用して複数の条件を組み合わせます。
+ キー以外の属性に基づいて項目をフィルタリングします。

**SDK for JavaScript (v3)**  
を使用して、複雑なフィルター式で DynamoDB テーブルをクエリします AWS SDK for JavaScript。  

```
const { DynamoDBClient, QueryCommand } = require("@aws-sdk/client-dynamodb");

/**
 * Queries a DynamoDB table with a complex filter expression
 * 
 * @param {Object} config - AWS SDK configuration object
 * @param {string} tableName - The name of the DynamoDB table
 * @param {string} partitionKeyName - The name of the partition key
 * @param {string} partitionKeyValue - The value of the partition key
 * @param {number|string} minViews - Minimum number of views for filtering
 * @param {number|string} minReplies - Minimum number of replies for filtering
 * @param {string} requiredTag - Tag that must be present in the item's tags set
 * @returns {Promise<Object>} - The query response
 */
async function queryWithComplexFilter(
  config,
  tableName,
  partitionKeyName,
  partitionKeyValue,
  minViews,
  minReplies,
  requiredTag
) {
  try {
    // Create DynamoDB client
    const client = new DynamoDBClient(config);

    // Construct the query input
    const input = {
      TableName: tableName,
      KeyConditionExpression: "#pk = :pkValue",
      FilterExpression: "views >= :minViews AND replies >= :minReplies AND contains(tags, :tag)",
      ExpressionAttributeNames: {
        "#pk": partitionKeyName
      },
      ExpressionAttributeValues: {
        ":pkValue": { S: partitionKeyValue },
        ":minViews": { N: minViews.toString() },
        ":minReplies": { N: minReplies.toString() },
        ":tag": { S: requiredTag }
      }
    };

    // Execute the query
    const command = new QueryCommand(input);
    return await client.send(command);
  } catch (error) {
    console.error(`Error querying with complex filter: ${error}`);
    throw error;
  }
}
```
+  API の詳細については、*AWS SDK for JavaScript API リファレンス*の「[Query](https://docs.aws.amazon.com/AWSJavaScriptSDK/v3/latest/client/dynamodb/command/QueryCommand)」を参照してください。

### 動的フィルター式を使用してテーブルをクエリする
<a name="dynamodb_Scenarios_QueryWithDynamicFilter_javascript_topic"></a>

以下のコード例は、動的フィルター式を使用してテーブルをクエリする方法を示しています。
+ ランタイムにフィルター式を動的に構築します。
+ ユーザー入力またはアプリケーション状態に基づいてフィルター条件を構築します。
+ 条件付きでフィルター条件を追加または削除します。

**SDK for JavaScript (v3)**  
を使用して動的に構築されたフィルター式を使用して DynamoDB テーブルをクエリします AWS SDK for JavaScript。  

```
const { DynamoDBClient, QueryCommand } = require("@aws-sdk/client-dynamodb");

async function queryWithDynamicFilter(
  config,
  tableName,
  partitionKeyName,
  partitionKeyValue,
  sortKeyName,
  sortKeyValue,
  filterParams = {}
) {
  try {
    // Create DynamoDB client
    const client = new DynamoDBClient(config);

    // Initialize filter expression components
    let filterExpressions = [];
    const expressionAttributeValues = {
      ":pkValue": { S: partitionKeyValue },
      ":skValue": { S: sortKeyValue }
    };
    const expressionAttributeNames = {
      "#pk": partitionKeyName,
      "#sk": sortKeyName
    };

    // Add status filter if provided
    if (filterParams.status) {
      filterExpressions.push("status = :status");
      expressionAttributeValues[":status"] = { S: filterParams.status };
    }

    // Add minimum views filter if provided
    if (filterParams.minViews !== undefined) {
      filterExpressions.push("views >= :minViews");
      expressionAttributeValues[":minViews"] = { N: filterParams.minViews.toString() };
    }

    // Add author filter if provided
    if (filterParams.author) {
      filterExpressions.push("author = :author");
      expressionAttributeValues[":author"] = { S: filterParams.author };
    }

    // Construct the query input
    const input = {
      TableName: tableName,
      KeyConditionExpression: "#pk = :pkValue AND #sk = :skValue"
    };

    // Add filter expression if any filters were provided
    if (filterExpressions.length > 0) {
      input.FilterExpression = filterExpressions.join(" AND ");
    }

    // Add expression attribute names and values
    input.ExpressionAttributeNames = expressionAttributeNames;
    input.ExpressionAttributeValues = expressionAttributeValues;

    // Execute the query
    const command = new QueryCommand(input);
    return await client.send(command);
  } catch (error) {
    console.error(`Error querying with dynamic filter: ${error}`);
    throw error;
  }
}
```
+  API の詳細については、*AWS SDK for JavaScript API リファレンス*の「[Query](https://docs.aws.amazon.com/AWSJavaScriptSDK/v3/latest/client/dynamodb/command/QueryCommand)」を参照してください。

### ネストされた属性を使用してテーブルをクエリする
<a name="dynamodb_Scenarios_QueryWithNestedAttributes_javascript_topic"></a>

以下のコード例は、ネストされた属性を使用してテーブルをクエリする方法を示しています。
+ DynamoDB 項目のネストされた属性を使用してアクセスおよびフィルタリングします。
+ ネストされた要素を参照するには、ドキュメントパス式を使用します。

**SDK for JavaScript (v3)**  
を使用して、ネストされた属性を持つ DynamoDB テーブルをクエリします AWS SDK for JavaScript。  

```
const { DynamoDBClient, QueryCommand } = require("@aws-sdk/client-dynamodb");

/**
 * Queries a DynamoDB table filtering on a nested attribute
 * 
 * @param {Object} config - AWS SDK configuration object
 * @param {string} tableName - The name of the DynamoDB table
 * @param {string} productId - The product ID to query by (partition key)
 * @param {string} category - The category to filter by (nested attribute)
 * @returns {Promise<Object>} - The query response
 */
async function queryWithNestedAttribute(
  config,
  tableName,
  productId,
  category
) {
  try {
    // Create DynamoDB client
    const client = new DynamoDBClient(config);

    // Construct the query input
    const input = {
      TableName: tableName,
      KeyConditionExpression: "product_id = :productId",
      FilterExpression: "details.category = :category",
      ExpressionAttributeValues: {
        ":productId": { S: productId },
        ":category": { S: category }
      }
    };

    // Execute the query
    const command = new QueryCommand(input);
    return await client.send(command);
  } catch (error) {
    console.error(`Error querying with nested attribute: ${error}`);
    throw error;
  }
}
```
+  API の詳細については、*AWS SDK for JavaScript API リファレンス*の「[Query](https://docs.aws.amazon.com/AWSJavaScriptSDK/v3/latest/client/dynamodb/command/QueryCommand)」を参照してください。

### ページ分割を使用してテーブルをクエリする
<a name="dynamodb_Scenarios_QueryWithPagination_javascript_topic"></a>

以下のコード例は、ページ分割を使用してテーブルをクエリする方法を示しています。
+ DynamoDB クエリ結果のページ分割を実装します。
+ LastEvaluatedKey を使用して後続のページを取得します。
+ Limit パラメータを使用して、ページあたりの項目数を制御します。

**SDK for JavaScript (v3)**  
を使用してページ分割で DynamoDB テーブルをクエリします AWS SDK for JavaScript。  

```
/**
 * Example demonstrating how to handle large query result sets in DynamoDB using pagination
 * 
 * This example shows:
 * - How to use pagination to handle large result sets
 * - How to use LastEvaluatedKey to retrieve the next page of results
 * - How to construct subsequent query requests using ExclusiveStartKey
 */
const { DynamoDBClient, QueryCommand } = require("@aws-sdk/client-dynamodb");

/**
 * Queries a DynamoDB table with pagination to handle large result sets
 * 
 * @param {Object} config - AWS SDK configuration object
 * @param {string} tableName - The name of the DynamoDB table
 * @param {string} partitionKeyName - The name of the partition key
 * @param {string} partitionKeyValue - The value of the partition key
 * @param {number} pageSize - Number of items per page
 * @returns {Promise<Array>} - All items from the query
 */
async function queryWithPagination(
  config,
  tableName,
  partitionKeyName,
  partitionKeyValue,
  pageSize = 25
) {
  try {
    // Create DynamoDB client
    const client = new DynamoDBClient(config);
    
    // Initialize variables for pagination
    let lastEvaluatedKey = undefined;
    const allItems = [];
    let pageCount = 0;
    
    // Loop until all pages are retrieved
    do {
      // Construct the query input
      const input = {
        TableName: tableName,
        KeyConditionExpression: "#pk = :pkValue",
        Limit: pageSize,
        ExpressionAttributeNames: {
          "#pk": partitionKeyName
        },
        ExpressionAttributeValues: {
          ":pkValue": { S: partitionKeyValue }
        }
      };
      
      // Add ExclusiveStartKey if we have a LastEvaluatedKey from a previous query
      if (lastEvaluatedKey) {
        input.ExclusiveStartKey = lastEvaluatedKey;
      }
      
      // Execute the query
      const command = new QueryCommand(input);
      const response = await client.send(command);
      
      // Process the current page of results
      pageCount++;
      console.log(`Processing page ${pageCount} with ${response.Items.length} items`);
      
      // Add the items from this page to our collection
      if (response.Items && response.Items.length > 0) {
        allItems.push(...response.Items);
      }
      
      // Get the LastEvaluatedKey for the next page
      lastEvaluatedKey = response.LastEvaluatedKey;
      
    } while (lastEvaluatedKey); // Continue until there are no more pages
    
    console.log(`Query complete. Retrieved ${allItems.length} items in ${pageCount} pages.`);
    return allItems;
  } catch (error) {
    console.error(`Error querying with pagination: ${error}`);
    throw error;
  }
}

/**
 * Example usage:
 * 
 * // Query all items in the "AWS DynamoDB" forum with pagination
 * const allItems = await queryWithPagination(
 *   { region: "us-west-2" },
 *   "ForumThreads",
 *   "ForumName",
 *   "AWS DynamoDB",
 *   25 // 25 items per page
 * );
 * 
 * console.log(`Total items retrieved: ${allItems.length}`);
 * 
 * // Notes on pagination:
 * // - LastEvaluatedKey contains the primary key of the last evaluated item
 * // - When LastEvaluatedKey is undefined/null, there are no more items to retrieve
 * // - ExclusiveStartKey tells DynamoDB where to start the next page
 * // - Pagination helps manage memory usage for large result sets
 * // - Each page requires a separate network request to DynamoDB
 */

module.exports = { queryWithPagination };
```
+  API の詳細については、*AWS SDK for JavaScript API リファレンス*の「[Query](https://docs.aws.amazon.com/AWSJavaScriptSDK/v3/latest/client/dynamodb/command/QueryCommand)」を参照してください。

### 強力な整合性のある読み込みを使用してテーブルをクエリする
<a name="dynamodb_Scenarios_QueryWithStronglyConsistentReads_javascript_topic"></a>

次のコード例は、強力な整合性のある読み込みを使用してテーブルをクエリする方法を示しています。
+ DynamoDB クエリの整合性レベルを設定します。
+ 強力な整合性のある読み込みを使用して最新のデータを取得します。
+ 結果整合性と強力な整合性のトレードオフを理解します。

**SDK for JavaScript (v3)**  
を使用して、設定可能な読み取り整合性で DynamoDB テーブルをクエリします AWS SDK for JavaScript。  

```
const { DynamoDBClient, QueryCommand } = require("@aws-sdk/client-dynamodb");

/**
 * Queries a DynamoDB table with configurable read consistency
 * 
 * @param {Object} config - AWS SDK configuration object
 * @param {string} tableName - The name of the DynamoDB table
 * @param {string} partitionKeyName - The name of the partition key
 * @param {string} partitionKeyValue - The value of the partition key
 * @param {boolean} useConsistentRead - Whether to use strongly consistent reads
 * @returns {Promise<Object>} - The query response
 */
async function queryWithConsistentRead(
  config,
  tableName,
  partitionKeyName,
  partitionKeyValue,
  useConsistentRead = false
) {
  try {
    // Create DynamoDB client
    const client = new DynamoDBClient(config);

    // Construct the query input
    const input = {
      TableName: tableName,
      KeyConditionExpression: "#pk = :pkValue",
      ExpressionAttributeNames: {
        "#pk": partitionKeyName
      },
      ExpressionAttributeValues: {
        ":pkValue": { S: partitionKeyValue }
      },
      ConsistentRead: useConsistentRead
    };

    // Execute the query
    const command = new QueryCommand(input);
    return await client.send(command);
  } catch (error) {
    console.error(`Error querying with consistent read: ${error}`);
    throw error;
  }
}
```
+  API の詳細については、*AWS SDK for JavaScript API リファレンス*の「[Query](https://docs.aws.amazon.com/AWSJavaScriptSDK/v3/latest/client/dynamodb/command/QueryCommand)」を参照してください。

### PartiQL SELECT を使用してデータをクエリする
<a name="dynamodb_PartiQLSelect_javascript_topic"></a>

次のコード例は、PartiQL SELECT ステートメントを使用してデータをクエリする方法を示しています。

**SDK for JavaScript (v3)**  
PartiQL SELECT ステートメントを使用して、DynamoDB テーブルから項目をクエリします AWS SDK for JavaScript。  

```
/**
 * This example demonstrates how to query items from a DynamoDB table using PartiQL.
 * It shows different ways to select data with various index types.
 */
import { DynamoDBClient } from "@aws-sdk/client-dynamodb";
import {
  DynamoDBDocumentClient,
  ExecuteStatementCommand,
  BatchExecuteStatementCommand,
} from "@aws-sdk/lib-dynamodb";

/**
 * Select all items from a DynamoDB table using PartiQL.
 * Note: This should be used with caution on large tables.
 * 
 * @param tableName - The name of the DynamoDB table
 * @returns The response from the ExecuteStatementCommand
 */
export const selectAllItems = async (tableName: string) => {
  const client = new DynamoDBClient({});
  const docClient = DynamoDBDocumentClient.from(client);

  const params = {
    Statement: `SELECT * FROM "${tableName}"`,
  };

  try {
    const data = await docClient.send(new ExecuteStatementCommand(params));
    console.log("Items retrieved successfully");
    return data;
  } catch (err) {
    console.error("Error retrieving items:", err);
    throw err;
  }
};

/**
 * Select an item by its primary key using PartiQL.
 * 
 * @param tableName - The name of the DynamoDB table
 * @param partitionKeyName - The name of the partition key attribute
 * @param partitionKeyValue - The value of the partition key
 * @returns The response from the ExecuteStatementCommand
 */
export const selectItemByPartitionKey = async (
  tableName: string,
  partitionKeyName: string,
  partitionKeyValue: string | number
) => {
  const client = new DynamoDBClient({});
  const docClient = DynamoDBDocumentClient.from(client);

  const params = {
    Statement: `SELECT * FROM "${tableName}" WHERE ${partitionKeyName} = ?`,
    Parameters: [partitionKeyValue],
  };

  try {
    const data = await docClient.send(new ExecuteStatementCommand(params));
    console.log("Item retrieved successfully");
    return data;
  } catch (err) {
    console.error("Error retrieving item:", err);
    throw err;
  }
};

/**
 * Select an item by its composite key (partition key + sort key) using PartiQL.
 * 
 * @param tableName - The name of the DynamoDB table
 * @param partitionKeyName - The name of the partition key attribute
 * @param partitionKeyValue - The value of the partition key
 * @param sortKeyName - The name of the sort key attribute
 * @param sortKeyValue - The value of the sort key
 * @returns The response from the ExecuteStatementCommand
 */
export const selectItemByCompositeKey = async (
  tableName: string,
  partitionKeyName: string,
  partitionKeyValue: string | number,
  sortKeyName: string,
  sortKeyValue: string | number
) => {
  const client = new DynamoDBClient({});
  const docClient = DynamoDBDocumentClient.from(client);

  const params = {
    Statement: `SELECT * FROM "${tableName}" WHERE ${partitionKeyName} = ? AND ${sortKeyName} = ?`,
    Parameters: [partitionKeyValue, sortKeyValue],
  };

  try {
    const data = await docClient.send(new ExecuteStatementCommand(params));
    console.log("Item retrieved successfully");
    return data;
  } catch (err) {
    console.error("Error retrieving item:", err);
    throw err;
  }
};

/**
 * Select items using a filter condition with PartiQL.
 * 
 * @param tableName - The name of the DynamoDB table
 * @param filterAttribute - The attribute to filter on
 * @param filterValue - The value to filter by
 * @returns The response from the ExecuteStatementCommand
 */
export const selectItemsWithFilter = async (
  tableName: string,
  filterAttribute: string,
  filterValue: string | number
) => {
  const client = new DynamoDBClient({});
  const docClient = DynamoDBDocumentClient.from(client);

  const params = {
    Statement: `SELECT * FROM "${tableName}" WHERE ${filterAttribute} = ?`,
    Parameters: [filterValue],
  };

  try {
    const data = await docClient.send(new ExecuteStatementCommand(params));
    console.log("Items retrieved successfully");
    return data;
  } catch (err) {
    console.error("Error retrieving items:", err);
    throw err;
  }
};

/**
 * Select items using a begins_with function for prefix matching.
 * This is useful for querying hierarchical data.
 * 
 * @param tableName - The name of the DynamoDB table
 * @param attributeName - The attribute to check for prefix
 * @param prefix - The prefix to match
 * @returns The response from the ExecuteStatementCommand
 */
export const selectItemsByPrefix = async (
  tableName: string,
  attributeName: string,
  prefix: string
) => {
  const client = new DynamoDBClient({});
  const docClient = DynamoDBDocumentClient.from(client);

  const params = {
    Statement: `SELECT * FROM "${tableName}" WHERE begins_with(${attributeName}, ?)`,
    Parameters: [prefix],
  };

  try {
    const data = await docClient.send(new ExecuteStatementCommand(params));
    console.log("Items retrieved successfully");
    return data;
  } catch (err) {
    console.error("Error retrieving items:", err);
    throw err;
  }
};

/**
 * Select items using a between condition for range queries.
 * 
 * @param tableName - The name of the DynamoDB table
 * @param attributeName - The attribute to check for range
 * @param startValue - The start value of the range
 * @param endValue - The end value of the range
 * @returns The response from the ExecuteStatementCommand
 */
export const selectItemsByRange = async (
  tableName: string,
  attributeName: string,
  startValue: number | string,
  endValue: number | string
) => {
  const client = new DynamoDBClient({});
  const docClient = DynamoDBDocumentClient.from(client);

  const params = {
    Statement: `SELECT * FROM "${tableName}" WHERE ${attributeName} BETWEEN ? AND ?`,
    Parameters: [startValue, endValue],
  };

  try {
    const data = await docClient.send(new ExecuteStatementCommand(params));
    console.log("Items retrieved successfully");
    return data;
  } catch (err) {
    console.error("Error retrieving items:", err);
    throw err;
  }
};

/**
 * Example usage showing how to select items with different index types
 */
export const selectExamples = async () => {
  // Select all items from a table (use with caution on large tables)
  await selectAllItems("UsersTable");

  // Select by partition key (simple primary key)
  await selectItemByPartitionKey("UsersTable", "userId", "user123");

  // Select by composite key (partition key + sort key)
  await selectItemByCompositeKey("OrdersTable", "orderId", "order456", "productId", "prod789");

  // Select with a filter condition (can use any attribute)
  await selectItemsWithFilter("UsersTable", "userType", "premium");

  // Select items with a prefix (useful for hierarchical data)
  await selectItemsByPrefix("ProductsTable", "category", "electronics");

  // Select items within a range (useful for numeric or date ranges)
  await selectItemsByRange("OrdersTable", "orderDate", "2023-01-01", "2023-12-31");
};
```
+ API の詳細については、「*AWS SDK for JavaScript API リファレンス*」の以下のトピックを参照してください。
  + [BatchExecuteStatement](https://docs.aws.amazon.com/AWSJavaScriptSDK/v3/latest/client/dynamodb/command/BatchExecuteStatementCommand)
  + [ExecuteStatement](https://docs.aws.amazon.com/AWSJavaScriptSDK/v3/latest/client/dynamodb/command/ExecuteStatementCommand)

### TTL 項目のクエリ
<a name="dynamodb_QueryFilteredTTL_javascript_topic"></a>

以下のコード例は、TTL 項目のクエリの開始方法を示しています。

**SDK for JavaScript (v3)**  
を使用して DynamoDB テーブルに TTL 項目を収集するためにフィルタリングされた式をクエリします AWS SDK for JavaScript。  

```
import { DynamoDBClient, QueryCommand } from "@aws-sdk/client-dynamodb";
import { marshall, unmarshall } from "@aws-sdk/util-dynamodb";

export const queryFiltered = async (tableName, primaryKey, region = 'us-east-1') => {
    const client = new DynamoDBClient({
        region: region,
        endpoint: `https://dynamodb.${region}.amazonaws.com`
    });

    const currentTime = Math.floor(Date.now() / 1000);

    const params = {
        TableName: tableName,
        KeyConditionExpression: "#pk = :pk",
        FilterExpression: "#ea > :ea",
        ExpressionAttributeNames: {
            "#pk": "primaryKey",
            "#ea": "expireAt"
        },
        ExpressionAttributeValues: marshall({
            ":pk": primaryKey,
            ":ea": currentTime
        })
    };

    try {
        const { Items } = await client.send(new QueryCommand(params));
        Items.forEach(item => {
            console.log(unmarshall(item))
        });
        return Items;
    } catch (err) {
        console.error(`Error querying items: ${err}`);
        throw err;
    }
}

// Example usage (commented out for testing)
// queryFiltered('your-table-name', 'your-partition-key-value');
```
+  API の詳細については、*AWS SDK for JavaScript API リファレンス*の「[Query](https://docs.aws.amazon.com/AWSJavaScriptSDK/v3/latest/client/dynamodb/command/QueryCommand)」を参照してください。

### 日付と時刻のパターンを使用してテーブルをクエリする
<a name="dynamodb_Scenario_DateTimeQueries_javascript_topic"></a>

次のコード例は、日付と時刻のパターンを使用してテーブルをクエリする方法を示しています。
+ DynamoDB に日付/時刻値を保存してクエリします。
+ ソートキーを使用して日付範囲クエリを実装します。
+ 有効なクエリを行うために日付文字列をフォーマットします。

**SDK for JavaScript (v3)**  
でソートキーの日付範囲を使用してクエリを実行します AWS SDK for JavaScript。  

```
const { DynamoDBClient, QueryCommand } = require("@aws-sdk/client-dynamodb");

/**
 * Queries a DynamoDB table for items within a specific date range on the sort key
 * 
 * @param {Object} config - AWS SDK configuration object
 * @param {string} tableName - The name of the DynamoDB table
 * @param {string} partitionKeyName - The name of the partition key
 * @param {string} partitionKeyValue - The value of the partition key
 * @param {string} sortKeyName - The name of the sort key (must be a date/time attribute)
 * @param {Date} startDate - The start date for the range query
 * @param {Date} endDate - The end date for the range query
 * @returns {Promise<Object>} - The query response
 */
async function queryByDateRangeOnSortKey(
  config,
  tableName,
  partitionKeyName,
  partitionKeyValue,
  sortKeyName,
  startDate,
  endDate
) {
  try {
    // Create DynamoDB client
    const client = new DynamoDBClient(config);

    // Format dates as ISO strings for DynamoDB
    const formattedStartDate = startDate.toISOString();
    const formattedEndDate = endDate.toISOString();

    // Construct the query input
    const input = {
      TableName: tableName,
      KeyConditionExpression: '#pk = :pkValue AND #sk BETWEEN :startDate AND :endDate',
      ExpressionAttributeNames: {
        "#pk": partitionKeyName,
        "#sk": sortKeyName
      },
      ExpressionAttributeValues: {
        ":pkValue": { S: partitionKeyValue },
        ":startDate": { S: formattedStartDate },
        ":endDate": { S: formattedEndDate }
      }
    };

    // Execute the query
    const command = new QueryCommand(input);
    return await client.send(command);
  } catch (error) {
    console.error(`Error querying by date range on sort key: ${error}`);
    throw error;
  }
}
```
で日時変数を使用してクエリを実行します AWS SDK for JavaScript。  

```
const { DynamoDBClient, QueryCommand } = require("@aws-sdk/client-dynamodb");

/**
 * Queries a DynamoDB table for items within a specific date range
 * 
 * @param {Object} config - AWS SDK configuration object
 * @param {string} tableName - The name of the DynamoDB table
 * @param {string} partitionKeyName - The name of the partition key
 * @param {string} partitionKeyValue - The value of the partition key
 * @param {string} dateKeyName - The name of the date attribute to filter on
 * @param {Date} startDate - The start date for the range query
 * @param {Date} endDate - The end date for the range query
 * @returns {Promise<Object>} - The query response
 */
async function queryByDateRange(
  config,
  tableName,
  partitionKeyName,
  partitionKeyValue,
  dateKeyName,
  startDate,
  endDate
) {
  try {
    // Create DynamoDB client
    const client = new DynamoDBClient(config);

    // Format dates as ISO strings for DynamoDB
    const formattedStartDate = startDate.toISOString();
    const formattedEndDate = endDate.toISOString();

    // Construct the query input
    const input = {
      TableName: tableName,
      KeyConditionExpression: `#pk = :pkValue AND #dateAttr BETWEEN :startDate AND :endDate`,
      ExpressionAttributeNames: {
        "#pk": partitionKeyName,
        "#dateAttr": dateKeyName
      },
      ExpressionAttributeValues: {
        ":pkValue": { S: partitionKeyValue },
        ":startDate": { S: formattedStartDate },
        ":endDate": { S: formattedEndDate }
      }
    };

    // Execute the query
    const command = new QueryCommand(input);
    return await client.send(command);
  } catch (error) {
    console.error(`Error querying by date range: ${error}`);
    throw error;
  }
}
```
+  API の詳細については、*AWS SDK for JavaScript API リファレンス*の「[Query](https://docs.aws.amazon.com/AWSJavaScriptSDK/v3/latest/client/dynamodb/command/QueryCommand)」を参照してください。

### 式順序の更新を理解する
<a name="dynamodb_Scenario_UpdateExpressionOrder_javascript_topic"></a>

次のコード例は、式順序の更新を理解する方法を示しています。
+ DynamoDB が更新式を処理する方法について説明します。
+ 更新式のオペレーションの順序を理解します。
+ 式の評価を理解することで、予期しない結果を回避できます。

**SDK for JavaScript (v3)**  
を使用して式の更新順序をデモンストレーションします AWS SDK for JavaScript。  

```
const { DynamoDBClient } = require("@aws-sdk/client-dynamodb");
const { 
  DynamoDBDocumentClient, 
  UpdateCommand,
  GetCommand,
  PutCommand
} = require("@aws-sdk/lib-dynamodb");

/**
 * Update an item with multiple actions in a single update expression.
 * 
 * This function demonstrates how to use multiple actions in a single update expression
 * and how DynamoDB processes these actions.
 * 
 * @param {Object} config - AWS configuration object
 * @param {string} tableName - The name of the DynamoDB table
 * @param {Object} key - The primary key of the item to update
 * @param {string} updateExpression - The update expression with multiple actions
 * @param {Object} [expressionAttributeNames] - Expression attribute name placeholders
 * @param {Object} [expressionAttributeValues] - Expression attribute value placeholders
 * @returns {Promise<Object>} - The response from DynamoDB
 */
async function updateWithMultipleActions(
  config,
  tableName,
  key,
  updateExpression,
  expressionAttributeNames,
  expressionAttributeValues
) {
  // Initialize the DynamoDB client
  const client = new DynamoDBClient(config);
  const docClient = DynamoDBDocumentClient.from(client);
  
  // Prepare the update parameters
  const updateParams = {
    TableName: tableName,
    Key: key,
    UpdateExpression: updateExpression,
    ReturnValues: "UPDATED_NEW"
  };
  
  // Add expression attribute names if provided
  if (expressionAttributeNames) {
    updateParams.ExpressionAttributeNames = expressionAttributeNames;
  }
  
  // Add expression attribute values if provided
  if (expressionAttributeValues) {
    updateParams.ExpressionAttributeValues = expressionAttributeValues;
  }
  
  // Execute the update
  const response = await docClient.send(new UpdateCommand(updateParams));
  
  return response;
}

/**
 * Demonstrate that variables hold copies of existing values before modifications.
 * 
 * This function creates an item with initial values, then updates it with an expression
 * that uses the values of attributes before they are modified in the same expression.
 * 
 * @param {Object} config - AWS configuration object
 * @param {string} tableName - The name of the DynamoDB table
 * @param {Object} key - The primary key of the item to create and update
 * @returns {Promise<Object>} - A dictionary containing the results of the demonstration
 */
async function demonstrateValueCopying(
  config,
  tableName,
  key
) {
  // Initialize the DynamoDB client
  const client = new DynamoDBClient(config);
  const docClient = DynamoDBDocumentClient.from(client);
  
  // Step 1: Create an item with initial values
  const initialItem = { ...key, a: 1, b: 2, c: 3 };
  
  await docClient.send(new PutCommand({
    TableName: tableName,
    Item: initialItem
  }));
  
  // Step 2: Get the item to verify initial state
  const responseBefore = await docClient.send(new GetCommand({
    TableName: tableName,
    Key: key
  }));
  
  const itemBefore = responseBefore.Item || {};
  
  // Step 3: Update the item with an expression that uses values before they are modified
  // This expression removes 'a', then sets 'b' to the value of 'a', and 'c' to the value of 'b'
  const updateResponse = await docClient.send(new UpdateCommand({
    TableName: tableName,
    Key: key,
    UpdateExpression: "REMOVE a SET b = a, c = b",
    ReturnValues: "UPDATED_NEW"
  }));
  
  // Step 4: Get the item to verify final state
  const responseAfter = await docClient.send(new GetCommand({
    TableName: tableName,
    Key: key
  }));
  
  const itemAfter = responseAfter.Item || {};
  
  // Return the results
  return {
    initialState: itemBefore,
    updateResponse: updateResponse,
    finalState: itemAfter
  };
}

/**
 * Demonstrate the order in which different action types are processed.
 * 
 * This function creates an item with initial values, then updates it with an expression
 * that includes multiple action types (SET, REMOVE, ADD, DELETE) to show the order
 * in which they are processed.
 * 
 * @param {Object} config - AWS configuration object
 * @param {string} tableName - The name of the DynamoDB table
 * @param {Object} key - The primary key of the item to create and update
 * @returns {Promise<Object>} - A dictionary containing the results of the demonstration
 */
async function demonstrateActionOrder(
  config,
  tableName,
  key
) {
  // Initialize the DynamoDB client
  const client = new DynamoDBClient(config);
  const docClient = DynamoDBDocumentClient.from(client);
  
  // Step 1: Create an item with initial values
  const initialItem = {
    ...key,
    counter: 10,
    set_attr: new Set(["A", "B", "C"]),
    to_remove: "This will be removed",
    to_modify: "Original value"
  };
  
  await docClient.send(new PutCommand({
    TableName: tableName,
    Item: initialItem
  }));
  
  // Step 2: Get the item to verify initial state
  const responseBefore = await docClient.send(new GetCommand({
    TableName: tableName,
    Key: key
  }));
  
  const itemBefore = responseBefore.Item || {};
  
  // Step 3: Update the item with multiple action types
  // The actions will be processed in this order: REMOVE, SET, ADD, DELETE
  const updateResponse = await docClient.send(new UpdateCommand({
    TableName: tableName,
    Key: key,
    UpdateExpression: "REMOVE to_remove SET to_modify = :new_value ADD counter :increment DELETE set_attr :elements",
    ExpressionAttributeValues: {
      ":new_value": "Updated value",
      ":increment": 5,
      ":elements": new Set(["B"])
    },
    ReturnValues: "UPDATED_NEW"
  }));
  
  // Step 4: Get the item to verify final state
  const responseAfter = await docClient.send(new GetCommand({
    TableName: tableName,
    Key: key
  }));
  
  const itemAfter = responseAfter.Item || {};
  
  // Return the results
  return {
    initialState: itemBefore,
    updateResponse: updateResponse,
    finalState: itemAfter
  };
}

/**
 * Update multiple attributes with a single SET action.
 * 
 * This function demonstrates how to update multiple attributes in a single SET action,
 * which is more efficient than using multiple separate update operations.
 * 
 * @param {Object} config - AWS configuration object
 * @param {string} tableName - The name of the DynamoDB table
 * @param {Object} key - The primary key of the item to update
 * @param {Object} attributes - The attributes to update and their new values
 * @returns {Promise<Object>} - The response from DynamoDB
 */
async function updateWithMultipleSetActions(
  config,
  tableName,
  key,
  attributes
) {
  // Initialize the DynamoDB client
  const client = new DynamoDBClient(config);
  const docClient = DynamoDBDocumentClient.from(client);
  
  // Build the update expression and expression attribute values
  let updateExpression = "SET ";
  const expressionAttributeValues = {};
  
  // Add each attribute to the update expression
  Object.entries(attributes).forEach(([attrName, attrValue], index) => {
    const valuePlaceholder = `:val${index}`;
    
    if (index > 0) {
      updateExpression += ", ";
    }
    updateExpression += `${attrName} = ${valuePlaceholder}`;
    
    expressionAttributeValues[valuePlaceholder] = attrValue;
  });
  
  // Execute the update
  const response = await docClient.send(new UpdateCommand({
    TableName: tableName,
    Key: key,
    UpdateExpression: updateExpression,
    ExpressionAttributeValues: expressionAttributeValues,
    ReturnValues: "UPDATED_NEW"
  }));
  
  return response;
}

/**
 * Update an attribute with a value from another attribute or a default value.
 * 
 * This function demonstrates how to use if_not_exists to conditionally copy a value
 * from one attribute to another, or use a default value if the source doesn't exist.
 * 
 * @param {Object} config - AWS configuration object
 * @param {string} tableName - The name of the DynamoDB table
 * @param {Object} key - The primary key of the item to update
 * @param {string} sourceAttribute - The attribute to copy the value from
 * @param {string} targetAttribute - The attribute to update
 * @param {any} defaultValue - The default value to use if the source attribute doesn't exist
 * @returns {Promise<Object>} - The response from DynamoDB
 */
async function updateWithConditionalValueCopying(
  config,
  tableName,
  key,
  sourceAttribute,
  targetAttribute,
  defaultValue
) {
  // Initialize the DynamoDB client
  const client = new DynamoDBClient(config);
  const docClient = DynamoDBDocumentClient.from(client);
  
  // Use if_not_exists to conditionally copy the value
  const response = await docClient.send(new UpdateCommand({
    TableName: tableName,
    Key: key,
    UpdateExpression: `SET ${targetAttribute} = if_not_exists(${sourceAttribute}, :default)`,
    ExpressionAttributeValues: {
      ":default": defaultValue
    },
    ReturnValues: "UPDATED_NEW"
  }));
  
  return response;
}

/**
 * Demonstrate complex update expressions with multiple operations on the same attribute.
 * 
 * This function shows how DynamoDB processes multiple operations on the same attribute
 * in a single update expression.
 * 
 * @param {Object} config - AWS configuration object
 * @param {string} tableName - The name of the DynamoDB table
 * @param {Object} key - The primary key of the item to create and update
 * @returns {Promise<Object>} - A dictionary containing the results of the demonstration
 */
async function demonstrateMultipleOperationsOnSameAttribute(
  config,
  tableName,
  key
) {
  // Initialize the DynamoDB client
  const client = new DynamoDBClient(config);
  const docClient = DynamoDBDocumentClient.from(client);
  
  // Step 1: Create an item with initial values
  const initialItem = {
    ...key,
    counter: 10,
    list_attr: [1, 2, 3],
    map_attr: {
      nested1: "value1",
      nested2: "value2"
    }
  };
  
  await docClient.send(new PutCommand({
    TableName: tableName,
    Item: initialItem
  }));
  
  // Step 2: Get the item to verify initial state
  const responseBefore = await docClient.send(new GetCommand({
    TableName: tableName,
    Key: key
  }));
  
  const itemBefore = responseBefore.Item || {};
  
  // Step 3: Update the item with multiple operations on the same attributes
  const updateResponse = await docClient.send(new UpdateCommand({
    TableName: tableName,
    Key: key,
    UpdateExpression: `
      SET counter = counter + :inc1,
          counter = counter + :inc2,
          map_attr.nested1 = :new_val1,
          map_attr.nested3 = :new_val3,
          list_attr[0] = list_attr[1],
          list_attr[1] = list_attr[2]
    `,
    ExpressionAttributeValues: {
      ":inc1": 5,
      ":inc2": 3,
      ":new_val1": "updated_value1",
      ":new_val3": "new_value3"
    },
    ReturnValues: "UPDATED_NEW"
  }));
  
  // Step 4: Get the item to verify final state
  const responseAfter = await docClient.send(new GetCommand({
    TableName: tableName,
    Key: key
  }));
  
  const itemAfter = responseAfter.Item || {};
  
  // Return the results
  return {
    initialState: itemBefore,
    updateResponse: updateResponse,
    finalState: itemAfter
  };
}
```
を使用した式の更新順序の使用例 AWS SDK for JavaScript。  

```
/**
 * Example of how to use update expression order of operations in DynamoDB.
 */
async function exampleUsage() {
  // Example parameters
  const config = { region: "us-west-2" };
  const tableName = "OrderProcessing";
  
  console.log("Demonstrating update expression order of operations in DynamoDB");
  
  try {
    // Example 1: Demonstrating value copying in update expressions
    console.log("\nExample 1: Demonstrating value copying in update expressions");
    const results1 = await demonstrateValueCopying(
      config,
      tableName,
      { OrderId: "order123" }
    );
    
    console.log("Initial state:", JSON.stringify(results1.initialState, null, 2));
    console.log("Update response:", JSON.stringify(results1.updateResponse, null, 2));
    console.log("Final state:", JSON.stringify(results1.finalState, null, 2));
    
    console.log("\nExplanation:");
    console.log("1. The initial state had a=1, b=2, c=3");
    console.log("2. The update expression 'REMOVE a SET b = a, c = b' did the following:");
    console.log("   - Copied the value of 'a' (which was 1) to be used for 'b'");
    console.log("   - Copied the value of 'b' (which was 2) to be used for 'c'");
    console.log("   - Removed the attribute 'a'");
    console.log("3. The final state has b=1, c=2, and 'a' is removed");
    console.log("4. This demonstrates that DynamoDB uses the values of attributes as they were BEFORE any modifications");
    
    // Example 2: Demonstrating the order of different action types
    console.log("\nExample 2: Demonstrating the order of different action types");
    const results2 = await demonstrateActionOrder(
      config,
      tableName,
      { OrderId: "order456" }
    );
    
    console.log("Initial state:", JSON.stringify(results2.initialState, null, 2));
    console.log("Update response:", JSON.stringify(results2.updateResponse, null, 2));
    console.log("Final state:", JSON.stringify(results2.finalState, null, 2));
    
    console.log("\nExplanation:");
    console.log("1. The update expression contained multiple action types: REMOVE, SET, ADD, DELETE");
    console.log("2. DynamoDB processes these actions in this order: REMOVE, SET, ADD, DELETE");
    console.log("3. First, 'to_remove' was removed");
    console.log("4. Then, 'to_modify' was set to a new value");
    console.log("5. Next, 'counter' was incremented by 5");
    console.log("6. Finally, 'B' was removed from the set attribute");
    
    // Example 3: Updating multiple attributes in a single SET action
    console.log("\nExample 3: Updating multiple attributes in a single SET action");
    const response3 = await updateWithMultipleSetActions(
      config,
      tableName,
      { OrderId: "order789" },
      {
        Status: "Shipped",
        ShippingDate: "2025-05-28",
        TrackingNumber: "1Z999AA10123456784"
      }
    );
    
    console.log("Multiple attributes updated successfully:", JSON.stringify(response3.Attributes, null, 2));
    
    // Example 4: Conditional value copying with if_not_exists
    console.log("\nExample 4: Conditional value copying with if_not_exists");
    const response4 = await updateWithConditionalValueCopying(
      config,
      tableName,
      { OrderId: "order101" },
      "PreferredShippingMethod",
      "ShippingMethod",
      "Standard"
    );
    
    console.log("Conditional value copying result:", JSON.stringify(response4.Attributes, null, 2));
    
    // Example 5: Multiple operations on the same attribute
    console.log("\nExample 5: Multiple operations on the same attribute");
    const results5 = await demonstrateMultipleOperationsOnSameAttribute(
      config,
      tableName,
      { OrderId: "order202" }
    );
    
    console.log("Initial state:", JSON.stringify(results5.initialState, null, 2));
    console.log("Update response:", JSON.stringify(results5.updateResponse, null, 2));
    console.log("Final state:", JSON.stringify(results5.finalState, null, 2));
    
    console.log("\nExplanation:");
    console.log("1. The counter was incremented twice (first by 5, then by 3) for a total of +8");
    console.log("2. The map attribute had one value updated and a new nested attribute added");
    console.log("3. The list attribute had values shifted (value at index 1 moved to index 0, value at index 2 moved to index 1)");
    console.log("4. All operations within the SET action are processed from left to right");
    
    // Key points about update expression order of operations
    console.log("\nKey Points About Update Expression Order of Operations:");
    console.log("1. Variables in expressions hold copies of attribute values as they existed BEFORE any modifications");
    console.log("2. Multiple actions in an update expression are processed in this order: REMOVE, SET, ADD, DELETE");
    console.log("3. Within each action type, operations are processed from left to right");
    console.log("4. You can reference the same attribute multiple times in an expression");
    console.log("5. You can use if_not_exists() to conditionally set values based on attribute existence");
    console.log("6. Using a single update expression with multiple actions is more efficient than multiple separate updates");
    console.log("7. The update expression is atomic - either all actions succeed or none do");
    
  } catch (error) {
    console.error("Error:", error);
  }
}
```
+  API の詳細については、*AWS SDK for JavaScript API リファレンス*の「[UpdateItem](https://docs.aws.amazon.com/AWSJavaScriptSDK/v3/latest/client/dynamodb/command/UpdateItemCommand)」を参照してください。

### テーブルのウォームスループット設定を更新する
<a name="dynamodb_UpdateTableWarmThroughput_javascript_topic"></a>

次のコード例は、テーブルのウォームスループット設定を更新する方法を示しています。

**SDK for JavaScript (v3)**  
 AWS SDK for JavaScriptを使用して既存の DynamoDB テーブルのウォームスループット設定を更新します。  

```
import { DynamoDBClient, UpdateTableCommand } from "@aws-sdk/client-dynamodb";

export async function updateDynamoDBTableWarmThroughput(
  tableName,
  tableReadUnits,
  tableWriteUnits,
  gsiName,
  gsiReadUnits,
  gsiWriteUnits,
  region = "us-east-1"
) {
  try {
    const ddbClient = new DynamoDBClient({ region: region });

    // Construct the update table request
    const updateTableRequest = {
      TableName: tableName,
      GlobalSecondaryIndexUpdates: [
        {
            Update: {
                IndexName: gsiName,
                WarmThroughput: {
                    ReadUnitsPerSecond: gsiReadUnits,
                    WriteUnitsPerSecond: gsiWriteUnits,
                },
            },
        },
      ],
      WarmThroughput: {
          ReadUnitsPerSecond: tableReadUnits,
          WriteUnitsPerSecond: tableWriteUnits,
      },
    };

    const command = new UpdateTableCommand(updateTableRequest);
    const response = await ddbClient.send(command);
    console.log(`Table updated successfully! Response: ${JSON.stringify(response)}`);
    return response;
  } catch (error) {
    console.error(`Error updating table: ${error}`);
    throw error;
  }
}

// Example usage (commented out for testing)
/*
updateDynamoDBTableWarmThroughput(
  'example-table',
  5, 5,
  'example-index',
  2, 2
);
*/
```
+  API の詳細については、*AWS SDK for JavaScript API リファレンス*の「[UpdateTable](https://docs.aws.amazon.com/AWSJavaScriptSDK/v3/latest/client/dynamodb/command/UpdateTableCommand)」を参照してください。

### 項目の TTL を更新する
<a name="dynamodb_UpdateItemTTL_javascript_topic"></a>

以下のコード例は、項目の TTL の更新方法を示しています。

**SDK for JavaScript (v3)**  

```
import { DynamoDBClient, UpdateItemCommand } from "@aws-sdk/client-dynamodb";
import { marshall, unmarshall } from "@aws-sdk/util-dynamodb";

export const updateItem = async (tableName, partitionKey, sortKey, region = 'us-east-1') => {
    const client = new DynamoDBClient({
        region: region,
        endpoint: `https://dynamodb.${region}.amazonaws.com`
    });

    const currentTime = Math.floor(Date.now() / 1000);
    const expireAt = Math.floor((Date.now() + 90 * 24 * 60 * 60 * 1000) / 1000);

    const params = {
        TableName: tableName,
        Key: marshall({
            partitionKey: partitionKey,
            sortKey: sortKey
        }),
        UpdateExpression: "SET updatedAt = :c, expireAt = :e",
        ExpressionAttributeValues: marshall({
            ":c": currentTime,
            ":e": expireAt
        }),
    };

    try {
        const data = await client.send(new UpdateItemCommand(params));
        const responseData = unmarshall(data.Attributes);
        console.log("Item updated successfully: %s", responseData);
        return responseData;
    } catch (err) {
        console.error("Error updating item:", err);
        throw err;
    }
}

// Example usage (commented out for testing)
// updateItem('your-table-name', 'your-partition-key-value', 'your-sort-key-value');
```
+  API の詳細については、*AWS SDK for JavaScript API リファレンス*の「[UpdateItem](https://docs.aws.amazon.com/AWSJavaScriptSDK/v3/latest/client/dynamodb/command/UpdateItemCommand)」を参照してください。

### PartiQL UPDATE を使用してデータを更新する
<a name="dynamodb_PartiQLUpdate_javascript_topic"></a>

次のコード例は、PartiQL UPDATE ステートメントを使用してデータを更新する方法を示しています。

**SDK for JavaScript (v3)**  
PartiQL UPDATE ステートメントを使用して DynamoDB テーブルの項目を更新します AWS SDK for JavaScript。  

```
/**
 * This example demonstrates how to update items in a DynamoDB table using PartiQL.
 * It shows different ways to update documents with various index types.
 */
import { DynamoDBClient } from "@aws-sdk/client-dynamodb";
import {
  DynamoDBDocumentClient,
  ExecuteStatementCommand,
  BatchExecuteStatementCommand,
} from "@aws-sdk/lib-dynamodb";

/**
 * Update a single attribute of an item using PartiQL.
 * 
 * @param tableName - The name of the DynamoDB table
 * @param partitionKeyName - The name of the partition key attribute
 * @param partitionKeyValue - The value of the partition key
 * @param attributeName - The name of the attribute to update
 * @param attributeValue - The new value for the attribute
 * @returns The response from the ExecuteStatementCommand
 */
export const updateSingleAttribute = async (
  tableName: string,
  partitionKeyName: string,
  partitionKeyValue: string | number,
  attributeName: string,
  attributeValue: any
) => {
  const client = new DynamoDBClient({});
  const docClient = DynamoDBDocumentClient.from(client);

  const params = {
    Statement: `UPDATE "${tableName}" SET ${attributeName} = ? WHERE ${partitionKeyName} = ?`,
    Parameters: [attributeValue, partitionKeyValue],
  };

  try {
    const data = await docClient.send(new ExecuteStatementCommand(params));
    console.log("Item updated successfully");
    return data;
  } catch (err) {
    console.error("Error updating item:", err);
    throw err;
  }
};

/**
 * Update multiple attributes of an item using PartiQL.
 * 
 * @param tableName - The name of the DynamoDB table
 * @param partitionKeyName - The name of the partition key attribute
 * @param partitionKeyValue - The value of the partition key
 * @param attributeUpdates - Object containing attribute names and their new values
 * @returns The response from the ExecuteStatementCommand
 */
export const updateMultipleAttributes = async (
  tableName: string,
  partitionKeyName: string,
  partitionKeyValue: string | number,
  attributeUpdates: Record<string, any>
) => {
  const client = new DynamoDBClient({});
  const docClient = DynamoDBDocumentClient.from(client);

  // Create SET clause for each attribute
  const setClause = Object.keys(attributeUpdates)
    .map((attr, index) => `${attr} = ?`)
    .join(", ");

  // Create parameters array with attribute values followed by the partition key value
  const parameters = [...Object.values(attributeUpdates), partitionKeyValue];

  const params = {
    Statement: `UPDATE "${tableName}" SET ${setClause} WHERE ${partitionKeyName} = ?`,
    Parameters: parameters,
  };

  try {
    const data = await docClient.send(new ExecuteStatementCommand(params));
    console.log("Item updated successfully");
    return data;
  } catch (err) {
    console.error("Error updating item:", err);
    throw err;
  }
};

/**
 * Update an item identified by a composite key (partition key + sort key) using PartiQL.
 * 
 * @param tableName - The name of the DynamoDB table
 * @param partitionKeyName - The name of the partition key attribute
 * @param partitionKeyValue - The value of the partition key
 * @param sortKeyName - The name of the sort key attribute
 * @param sortKeyValue - The value of the sort key
 * @param attributeName - The name of the attribute to update
 * @param attributeValue - The new value for the attribute
 * @returns The response from the ExecuteStatementCommand
 */
export const updateItemWithCompositeKey = async (
  tableName: string,
  partitionKeyName: string,
  partitionKeyValue: string | number,
  sortKeyName: string,
  sortKeyValue: string | number,
  attributeName: string,
  attributeValue: any
) => {
  const client = new DynamoDBClient({});
  const docClient = DynamoDBDocumentClient.from(client);

  const params = {
    Statement: `UPDATE "${tableName}" SET ${attributeName} = ? WHERE ${partitionKeyName} = ? AND ${sortKeyName} = ?`,
    Parameters: [attributeValue, partitionKeyValue, sortKeyValue],
  };

  try {
    const data = await docClient.send(new ExecuteStatementCommand(params));
    console.log("Item updated successfully");
    return data;
  } catch (err) {
    console.error("Error updating item:", err);
    throw err;
  }
};

/**
 * Update an item with a condition to ensure the update only happens if a condition is met.
 * 
 * @param tableName - The name of the DynamoDB table
 * @param partitionKeyName - The name of the partition key attribute
 * @param partitionKeyValue - The value of the partition key
 * @param attributeName - The name of the attribute to update
 * @param attributeValue - The new value for the attribute
 * @param conditionAttribute - The attribute to check in the condition
 * @param conditionValue - The value to compare against in the condition
 * @returns The response from the ExecuteStatementCommand
 */
export const updateItemWithCondition = async (
  tableName: string,
  partitionKeyName: string,
  partitionKeyValue: string | number,
  attributeName: string,
  attributeValue: any,
  conditionAttribute: string,
  conditionValue: any
) => {
  const client = new DynamoDBClient({});
  const docClient = DynamoDBDocumentClient.from(client);

  const params = {
    Statement: `UPDATE "${tableName}" SET ${attributeName} = ? WHERE ${partitionKeyName} = ? AND ${conditionAttribute} = ?`,
    Parameters: [attributeValue, partitionKeyValue, conditionValue],
  };

  try {
    const data = await docClient.send(new ExecuteStatementCommand(params));
    console.log("Item updated with condition successfully");
    return data;
  } catch (err) {
    console.error("Error updating item with condition:", err);
    throw err;
  }
};

/**
 * Batch update multiple items using PartiQL.
 * 
 * @param tableName - The name of the DynamoDB table
 * @param updates - Array of objects containing key and update information
 * @returns The response from the BatchExecuteStatementCommand
 */
export const batchUpdateItems = async (
  tableName: string,
  updates: Array<{
    partitionKeyName: string;
    partitionKeyValue: string | number;
    attributeName: string;
    attributeValue: any;
  }>
) => {
  const client = new DynamoDBClient({});
  const docClient = DynamoDBDocumentClient.from(client);

  // Create statements for each update
  const statements = updates.map((update) => {
    return {
      Statement: `UPDATE "${tableName}" SET ${update.attributeName} = ? WHERE ${update.partitionKeyName} = ?`,
      Parameters: [update.attributeValue, update.partitionKeyValue],
    };
  });

  const params = {
    Statements: statements,
  };

  try {
    const data = await docClient.send(new BatchExecuteStatementCommand(params));
    console.log("Items batch updated successfully");
    return data;
  } catch (err) {
    console.error("Error batch updating items:", err);
    throw err;
  }
};

/**
 * Example usage showing how to update items with different index types
 */
export const updateExamples = async () => {
  // Update a single attribute using a simple primary key
  await updateSingleAttribute("UsersTable", "userId", "user123", "email", "newemail@example.com");

  // Update multiple attributes at once
  await updateMultipleAttributes("UsersTable", "userId", "user123", {
    email: "newemail@example.com",
    name: "John Smith",
    lastLogin: new Date().toISOString(),
  });

  // Update an item with a composite key (partition key + sort key)
  await updateItemWithCompositeKey(
    "OrdersTable",
    "orderId",
    "order456",
    "productId",
    "prod789",
    "quantity",
    5
  );

  // Update with a condition
  await updateItemWithCondition(
    "UsersTable",
    "userId",
    "user123",
    "userStatus",
    "active",
    "userType",
    "premium"
  );

  // Batch update multiple items
  await batchUpdateItems("UsersTable", [
    {
      partitionKeyName: "userId",
      partitionKeyValue: "user123",
      attributeName: "lastLogin",
      attributeValue: new Date().toISOString(),
    },
    {
      partitionKeyName: "userId",
      partitionKeyValue: "user456",
      attributeName: "lastLogin",
      attributeValue: new Date().toISOString(),
    },
  ]);
};
```
+ API の詳細については、「*AWS SDK for JavaScript API リファレンス*」の以下のトピックを参照してください。
  + [BatchExecuteStatement](https://docs.aws.amazon.com/AWSJavaScriptSDK/v3/latest/client/dynamodb/command/BatchExecuteStatementCommand)
  + [ExecuteStatement](https://docs.aws.amazon.com/AWSJavaScriptSDK/v3/latest/client/dynamodb/command/ExecuteStatementCommand)

### API Gateway を使用して Lambda 関数を呼び出す
<a name="cross_LambdaAPIGateway_javascript_topic"></a>

次のコード例は、Amazon API Gateway によって呼び出される AWS Lambda 関数を作成する方法を示しています。

**SDK for JavaScript (v3)**  
 Lambda JavaScript ランタイム API を使用して AWS Lambda 関数を作成する方法を示します。この例では、さまざまな AWS サービスを呼び出して、特定のユースケースを実行します。この例では、Amazon API Gateway によって呼び出される Lambda 関数を作成する方法を示します。この関数は、Amazon DynamoDB テーブルをスキャンして、Amazon Simple Notification Service (Amazon SNS) を使用して、従業員に年間の記念日を祝福するテキストメッセージを送信します。  
 完全なソースコードとセットアップおよび実行の手順については、[GitHub](https://github.com/awsdocs/aws-doc-sdk-examples/tree/main/javascriptv3/example_code/cross-services/lambda-api-gateway) で完全な例を参照してください。  
この例は、[AWS SDK for JavaScript v3 デベロッパーガイド](https://docs.aws.amazon.com/sdk-for-javascript/v3/developer-guide/api-gateway-invoking-lambda-example.html)でも使用できます。  

**この例で使用されているサービス**
+ API ゲートウェイ
+ DynamoDB
+ Lambda
+ Amazon SNS

### アトミックカウンタオペレーションを使用する
<a name="dynamodb_Scenario_AtomicCounterOperations_javascript_topic"></a>

次のコード例は、DynamoDB でアトミックカウンタオペレーションを使用する方法を示しています。
+ ADD および SET オペレーションを使用してカウンタをアトミックに増分します。
+ 存在しない可能性のあるカウンターを安全に増分します。
+ カウンターオペレーションに楽観的ロックを実装します。

**SDK for JavaScript (v3)**  
を使用してアトミックカウンターオペレーションをデモンストレーションします AWS SDK for JavaScript。  

```
const { DynamoDBClient } = require("@aws-sdk/client-dynamodb");
const { 
  DynamoDBDocumentClient, 
  UpdateCommand,
  GetCommand
} = require("@aws-sdk/lib-dynamodb");

/**
 * Increment a counter using the ADD operation.
 * 
 * This function demonstrates using the ADD operation for atomic increments.
 * The ADD operation is atomic and is the recommended way to increment counters.
 * 
 * @param {Object} config - AWS configuration object
 * @param {string} tableName - The name of the DynamoDB table
 * @param {Object} key - The key of the item to update
 * @param {string} counterName - The name of the counter attribute
 * @param {number} incrementValue - The value to increment by
 * @returns {Promise<Object>} - The response from DynamoDB
 */
async function incrementCounterWithAdd(
  config,
  tableName,
  key,
  counterName,
  incrementValue
) {
  // Initialize the DynamoDB client
  const client = new DynamoDBClient(config);
  const docClient = DynamoDBDocumentClient.from(client);
  
  // Define the update parameters using ADD
  const params = {
    TableName: tableName,
    Key: key,
    UpdateExpression: `ADD ${counterName} :increment`,
    ExpressionAttributeValues: {
      ":increment": incrementValue
    },
    ReturnValues: "UPDATED_NEW"
  };
  
  // Perform the update operation
  const response = await docClient.send(new UpdateCommand(params));
  
  return response;
}

/**
 * Increment a counter using the SET operation with an expression.
 * 
 * This function demonstrates using the SET operation with an expression for increments.
 * While this approach works, it's less idiomatic for simple increments than using ADD.
 * 
 * @param {Object} config - AWS configuration object
 * @param {string} tableName - The name of the DynamoDB table
 * @param {Object} key - The key of the item to update
 * @param {string} counterName - The name of the counter attribute
 * @param {number} incrementValue - The value to increment by
 * @returns {Promise<Object>} - The response from DynamoDB
 */
async function incrementCounterWithSet(
  config,
  tableName,
  key,
  counterName,
  incrementValue
) {
  // Initialize the DynamoDB client
  const client = new DynamoDBClient(config);
  const docClient = DynamoDBDocumentClient.from(client);
  
  // Define the update parameters using SET with an expression
  const params = {
    TableName: tableName,
    Key: key,
    UpdateExpression: `SET ${counterName} = ${counterName} + :increment`,
    ExpressionAttributeValues: {
      ":increment": incrementValue
    },
    ReturnValues: "UPDATED_NEW"
  };
  
  // Perform the update operation
  const response = await docClient.send(new UpdateCommand(params));
  
  return response;
}

/**
 * Increment a counter safely, handling the case where the counter might not exist.
 * 
 * This function demonstrates using the if_not_exists function with SET to safely
 * increment a counter that might not exist yet.
 * 
 * @param {Object} config - AWS configuration object
 * @param {string} tableName - The name of the DynamoDB table
 * @param {Object} key - The key of the item to update
 * @param {string} counterName - The name of the counter attribute
 * @param {number} incrementValue - The value to increment by
 * @param {number} defaultValue - The default value if the counter doesn't exist
 * @returns {Promise<Object>} - The response from DynamoDB
 */
async function incrementCounterSafely(
  config,
  tableName,
  key,
  counterName,
  incrementValue,
  defaultValue = 0
) {
  // Initialize the DynamoDB client
  const client = new DynamoDBClient(config);
  const docClient = DynamoDBDocumentClient.from(client);
  
  // Define the update parameters using SET with if_not_exists
  const params = {
    TableName: tableName,
    Key: key,
    UpdateExpression: `SET ${counterName} = if_not_exists(${counterName}, :default) + :increment`,
    ExpressionAttributeValues: {
      ":increment": incrementValue,
      ":default": defaultValue
    },
    ReturnValues: "UPDATED_NEW"
  };
  
  // Perform the update operation
  const response = await docClient.send(new UpdateCommand(params));
  
  return response;
}

/**
 * Increment a counter with optimistic locking to prevent race conditions.
 * 
 * This function demonstrates using a condition expression to implement optimistic
 * locking, which prevents race conditions when multiple processes try to update
 * the same counter.
 * 
 * @param {Object} config - AWS configuration object
 * @param {string} tableName - The name of the DynamoDB table
 * @param {Object} key - The key of the item to update
 * @param {string} counterName - The name of the counter attribute
 * @param {number} incrementValue - The value to increment by
 * @param {number} expectedValue - The expected current value of the counter
 * @returns {Promise<Object>} - The response from DynamoDB
 */
async function incrementCounterWithLocking(
  config,
  tableName,
  key,
  counterName,
  incrementValue,
  expectedValue
) {
  // Initialize the DynamoDB client
  const client = new DynamoDBClient(config);
  const docClient = DynamoDBDocumentClient.from(client);
  
  // Define the update parameters with a condition expression
  const params = {
    TableName: tableName,
    Key: key,
    UpdateExpression: `SET ${counterName} = ${counterName} + :increment`,
    ConditionExpression: `${counterName} = :expected`,
    ExpressionAttributeValues: {
      ":increment": incrementValue,
      ":expected": expectedValue
    },
    ReturnValues: "UPDATED_NEW"
  };
  
  try {
    // Perform the update operation
    const response = await docClient.send(new UpdateCommand(params));
    return {
      success: true,
      data: response
    };
  } catch (error) {
    // Check if the error is due to the condition check failing
    if (error.name === "ConditionalCheckFailedException") {
      return {
        success: false,
        error: "Optimistic locking failed: the counter value has changed"
      };
    }
    // Re-throw other errors
    throw error;
  }
}

/**
 * Get the current value of a counter.
 * 
 * Helper function to retrieve the current value of a counter attribute.
 * 
 * @param {Object} config - AWS configuration object
 * @param {string} tableName - The name of the DynamoDB table
 * @param {Object} key - The key of the item to get
 * @param {string} counterName - The name of the counter attribute
 * @returns {Promise<number|null>} - The current counter value or null if not found
 */
async function getCounterValue(
  config,
  tableName,
  key,
  counterName
) {
  // Initialize the DynamoDB client
  const client = new DynamoDBClient(config);
  const docClient = DynamoDBDocumentClient.from(client);
  
  // Define the get parameters
  const params = {
    TableName: tableName,
    Key: key
  };
  
  // Perform the get operation
  const response = await docClient.send(new GetCommand(params));
  
  // Return the counter value if it exists, otherwise null
  return response.Item && counterName in response.Item
    ? response.Item[counterName]
    : null;
}
```
でのアトミックカウンターオペレーションの使用例 AWS SDK for JavaScript。  

```
/**
 * Example of how to use the atomic counter operations.
 */
async function exampleUsage() {
  // Example parameters
  const config = { region: "us-west-2" };
  const tableName = "Products";
  const key = { ProductId: "P12345" };
  const counterName = "ViewCount";
  const incrementValue = 1;
  
  console.log("Demonstrating different approaches to increment counters in DynamoDB");
  
  try {
    // Example 1: Using ADD operation (recommended for simple increments)
    console.log("\nExample 1: Incrementing counter with ADD operation");
    const response1 = await incrementCounterWithAdd(
      config,
      tableName,
      key,
      counterName,
      incrementValue
    );
    
    console.log(`Counter incremented to: ${response1.Attributes[counterName]}`);
    
    // Example 2: Using SET operation with an expression
    console.log("\nExample 2: Incrementing counter with SET operation");
    const response2 = await incrementCounterWithSet(
      config,
      tableName,
      key,
      counterName,
      incrementValue
    );
    
    console.log(`Counter incremented to: ${response2.Attributes[counterName]}`);
    
    // Example 3: Safely incrementing a counter that might not exist
    console.log("\nExample 3: Safely incrementing counter that might not exist");
    const newKey = { ProductId: "P67890" };
    const response3 = await incrementCounterSafely(
      config,
      tableName,
      newKey,
      counterName,
      incrementValue,
      0
    );
    
    console.log(`Counter initialized and incremented to: ${response3.Attributes[counterName]}`);
    
    // Example 4: Incrementing with optimistic locking
    console.log("\nExample 4: Incrementing with optimistic locking");
    
    // First, get the current counter value
    const currentValue = await getCounterValue(config, tableName, key, counterName);
    console.log(`Current counter value: ${currentValue}`);
    
    // Then, try to increment with optimistic locking
    const response4 = await incrementCounterWithLocking(
      config,
      tableName,
      key,
      counterName,
      incrementValue,
      currentValue
    );
    
    if (response4.success) {
      console.log(`Counter successfully incremented to: ${response4.data.Attributes[counterName]}`);
    } else {
      console.log(response4.error);
    }
    
    // Explain the differences between ADD and SET
    console.log("\nKey differences between ADD and SET for counter operations:");
    console.log("1. ADD is more concise and idiomatic for simple increments");
    console.log("2. SET with expressions is more flexible for complex operations");
    console.log("3. Both operations are atomic and safe for concurrent updates");
    console.log("4. SET with if_not_exists is required when the attribute might not exist");
    console.log("5. Optimistic locking can be added to either approach for additional safety");
    
  } catch (error) {
    console.error("Error:", error);
  }
}
```
+  API の詳細については、*AWS SDK for JavaScript API リファレンス*の「[UpdateItem](https://docs.aws.amazon.com/AWSJavaScriptSDK/v3/latest/client/dynamodb/command/UpdateItemCommand)」を参照してください。

### 条件付きオペレーションを使用する
<a name="dynamodb_Scenario_ConditionalOperations_javascript_topic"></a>

次のコード例は、DynamoDB で条件付きオペレーションを使用する方法を示しています。
+ データの上書きを防ぐため、条件付き書き込みを実装します。
+ 条件式を使用してビジネスルールを適用します。
+ 条件付きチェックの失敗を適切に処理します。

**SDK for JavaScript (v3)**  
を使用して条件付きオペレーションをデモンストレーションします AWS SDK for JavaScript。  

```
const { DynamoDBClient } = require("@aws-sdk/client-dynamodb");
const { 
  DynamoDBDocumentClient, 
  UpdateCommand,
  DeleteCommand,
  GetCommand,
  PutCommand
} = require("@aws-sdk/lib-dynamodb");

/**
 * Perform a conditional update operation.
 * 
 * This function demonstrates how to update an item only if a condition is met.
 * 
 * @param {Object} config - AWS configuration object
 * @param {string} tableName - The name of the DynamoDB table
 * @param {Object} key - The key of the item to update
 * @param {string} conditionAttribute - The attribute to check in the condition
 * @param {any} conditionValue - The value to compare against
 * @param {string} updateAttribute - The attribute to update
 * @param {any} updateValue - The new value to set
 * @returns {Promise<Object>} - Result of the operation
 */
async function conditionalUpdate(
  config,
  tableName,
  key,
  conditionAttribute,
  conditionValue,
  updateAttribute,
  updateValue
) {
  // Initialize the DynamoDB client
  const client = new DynamoDBClient(config);
  const docClient = DynamoDBDocumentClient.from(client);
  
  // Define the update parameters with a condition expression
  const params = {
    TableName: tableName,
    Key: key,
    UpdateExpression: `SET ${updateAttribute} = :value`,
    ConditionExpression: `${conditionAttribute} = :condition`,
    ExpressionAttributeValues: {
      ":value": updateValue,
      ":condition": conditionValue
    },
    ReturnValues: "UPDATED_NEW"
  };
  
  try {
    // Perform the update operation
    const response = await docClient.send(new UpdateCommand(params));
    
    return {
      success: true,
      message: "Condition was met and update was performed",
      updatedAttributes: response.Attributes
    };
  } catch (error) {
    // Check if the error is due to the condition check failing
    if (error.name === "ConditionalCheckFailedException") {
      return {
        success: false,
        message: "Condition was not met, update was not performed",
        error: "ConditionalCheckFailedException"
      };
    }
    
    // Re-throw other errors
    throw error;
  }
}

/**
 * Perform a conditional delete operation.
 * 
 * This function demonstrates how to delete an item only if a condition is met.
 * 
 * @param {Object} config - AWS configuration object
 * @param {string} tableName - The name of the DynamoDB table
 * @param {Object} key - The key of the item to delete
 * @param {string} conditionAttribute - The attribute to check in the condition
 * @param {any} conditionValue - The value to compare against
 * @returns {Promise<Object>} - Result of the operation
 */
async function conditionalDelete(
  config,
  tableName,
  key,
  conditionAttribute,
  conditionValue
) {
  // Initialize the DynamoDB client
  const client = new DynamoDBClient(config);
  const docClient = DynamoDBDocumentClient.from(client);
  
  // Define the delete parameters with a condition expression
  const params = {
    TableName: tableName,
    Key: key,
    ConditionExpression: `${conditionAttribute} = :condition`,
    ExpressionAttributeValues: {
      ":condition": conditionValue
    },
    ReturnValues: "ALL_OLD"
  };
  
  try {
    // Perform the delete operation
    const response = await docClient.send(new DeleteCommand(params));
    
    return {
      success: true,
      message: "Condition was met and item was deleted",
      deletedItem: response.Attributes
    };
  } catch (error) {
    // Check if the error is due to the condition check failing
    if (error.name === "ConditionalCheckFailedException") {
      return {
        success: false,
        message: "Condition was not met, item was not deleted",
        error: "ConditionalCheckFailedException"
      };
    }
    
    // Re-throw other errors
    throw error;
  }
}

/**
 * Implement optimistic locking with a version number.
 * 
 * This function demonstrates how to use a version number for optimistic locking
 * to prevent race conditions when multiple processes update the same item.
 * 
 * @param {Object} config - AWS configuration object
 * @param {string} tableName - The name of the DynamoDB table
 * @param {Object} key - The key of the item to update
 * @param {Object} updates - The attributes to update
 * @param {number} expectedVersion - The expected current version number
 * @returns {Promise<Object>} - Result of the operation
 */
async function updateWithOptimisticLocking(
  config,
  tableName,
  key,
  updates,
  expectedVersion
) {
  // Initialize the DynamoDB client
  const client = new DynamoDBClient(config);
  const docClient = DynamoDBDocumentClient.from(client);
  
  // Build the update expression
  const updateExpressions = [];
  const expressionAttributeValues = {
    ":expectedVersion": expectedVersion,
    ":newVersion": expectedVersion + 1
  };
  
  // Add each update to the expression
  Object.entries(updates).forEach(([attribute, value], index) => {
    updateExpressions.push(`${attribute} = :val${index}`);
    expressionAttributeValues[`:val${index}`] = value;
  });
  
  // Add the version update
  updateExpressions.push("version = :newVersion");
  
  // Define the update parameters with a condition expression
  const params = {
    TableName: tableName,
    Key: key,
    UpdateExpression: `SET ${updateExpressions.join(", ")}`,
    ConditionExpression: "version = :expectedVersion",
    ExpressionAttributeValues: expressionAttributeValues,
    ReturnValues: "UPDATED_NEW"
  };
  
  try {
    // Perform the update operation
    const response = await docClient.send(new UpdateCommand(params));
    
    return {
      success: true,
      message: "Update succeeded with optimistic locking",
      newVersion: expectedVersion + 1,
      updatedAttributes: response.Attributes
    };
  } catch (error) {
    // Check if the error is due to the condition check failing
    if (error.name === "ConditionalCheckFailedException") {
      return {
        success: false,
        message: "Optimistic locking failed: the item was modified by another process",
        error: "ConditionalCheckFailedException"
      };
    }
    
    // Re-throw other errors
    throw error;
  }
}

/**
 * Implement a conditional write that creates an item only if it doesn't exist.
 * 
 * This function demonstrates how to use attribute_not_exists to create an item
 * only if it doesn't already exist (similar to an "INSERT IF NOT EXISTS" operation).
 * 
 * @param {Object} config - AWS configuration object
 * @param {string} tableName - The name of the DynamoDB table
 * @param {Object} item - The item to create
 * @returns {Promise<Object>} - Result of the operation
 */
async function createIfNotExists(
  config,
  tableName,
  item
) {
  // Initialize the DynamoDB client
  const client = new DynamoDBClient(config);
  const docClient = DynamoDBDocumentClient.from(client);
  
  // Extract the primary key attributes
  const keyAttributes = Object.keys(item).filter(attr => 
    attr === "id" || attr === "ID" || attr === "Id" || 
    attr.endsWith("Id") || attr.endsWith("ID") || 
    attr.endsWith("Key")
  );
  
  if (keyAttributes.length === 0) {
    throw new Error("Could not determine primary key attributes");
  }
  
  // Create a condition expression that checks if the item doesn't exist
  const conditionExpression = `attribute_not_exists(${keyAttributes[0]})`;
  
  // Define the put parameters with a condition expression
  const params = {
    TableName: tableName,
    Item: item,
    ConditionExpression: conditionExpression
  };
  
  try {
    // Perform the put operation
    await docClient.send(new PutCommand(params));
    
    return {
      success: true,
      message: "Item was created because it didn't exist",
      item
    };
  } catch (error) {
    // Check if the error is due to the condition check failing
    if (error.name === "ConditionalCheckFailedException") {
      return {
        success: false,
        message: "Item already exists, creation was skipped",
        error: "ConditionalCheckFailedException"
      };
    }
    
    // Re-throw other errors
    throw error;
  }
}

/**
 * Get the current value of an item.
 * 
 * Helper function to retrieve the current value of an item.
 * 
 * @param {Object} config - AWS configuration object
 * @param {string} tableName - The name of the DynamoDB table
 * @param {Object} key - The key of the item to get
 * @returns {Promise<Object|null>} - The item or null if not found
 */
async function getItem(
  config,
  tableName,
  key
) {
  // Initialize the DynamoDB client
  const client = new DynamoDBClient(config);
  const docClient = DynamoDBDocumentClient.from(client);
  
  // Define the get parameters
  const params = {
    TableName: tableName,
    Key: key
  };
  
  // Perform the get operation
  const response = await docClient.send(new GetCommand(params));
  
  // Return the item if it exists, otherwise null
  return response.Item || null;
}
```
での条件付きオペレーションの使用例 AWS SDK for JavaScript。  

```
/**
 * Example of how to use conditional operations.
 */
async function exampleUsage() {
  // Example parameters
  const config = { region: "us-west-2" };
  const tableName = "Products";
  const key = { ProductId: "P12345" };
  
  console.log("Demonstrating conditional operations in DynamoDB");
  
  try {
    // Example 1: Conditional update based on attribute value
    console.log("\nExample 1: Conditional update based on attribute value");
    const updateResult = await conditionalUpdate(
      config,
      tableName,
      key,
      "Category",
      "Electronics",
      "Price",
      299.99
    );
    
    console.log(`Result: ${updateResult.message}`);
    if (updateResult.success) {
      console.log("Updated attributes:", updateResult.updatedAttributes);
    }
    
    // Example 2: Conditional delete based on attribute value
    console.log("\nExample 2: Conditional delete based on attribute value");
    const deleteResult = await conditionalDelete(
      config,
      tableName,
      key,
      "InStock",
      false
    );
    
    console.log(`Result: ${deleteResult.message}`);
    if (deleteResult.success) {
      console.log("Deleted item:", deleteResult.deletedItem);
    }
    
    // Example 3: Optimistic locking with version number
    console.log("\nExample 3: Optimistic locking with version number");
    
    // First, get the current item to check its version
    const currentItem = await getItem(config, tableName, { ProductId: "P67890" });
    const currentVersion = currentItem ? (currentItem.version || 0) : 0;
    
    console.log(`Current version: ${currentVersion}`);
    
    // Then, update with optimistic locking
    const lockingResult = await updateWithOptimisticLocking(
      config,
      tableName,
      { ProductId: "P67890" },
      {
        Name: "Updated Product Name",
        Description: "This is an updated description"
      },
      currentVersion
    );
    
    console.log(`Result: ${lockingResult.message}`);
    if (lockingResult.success) {
      console.log(`New version: ${lockingResult.newVersion}`);
      console.log("Updated attributes:", lockingResult.updatedAttributes);
    }
    
    // Example 4: Create item only if it doesn't exist
    console.log("\nExample 4: Create item only if it doesn't exist");
    const createResult = await createIfNotExists(
      config,
      tableName,
      {
        ProductId: "P99999",
        Name: "New Product",
        Category: "Accessories",
        Price: 19.99,
        InStock: true
      }
    );
    
    console.log(`Result: ${createResult.message}`);
    if (createResult.success) {
      console.log("Created item:", createResult.item);
    }
    
    // Explain conditional operations
    console.log("\nKey points about conditional operations:");
    console.log("1. Conditional operations only succeed if the condition is met");
    console.log("2. ConditionalCheckFailedException indicates the condition wasn't met");
    console.log("3. Optimistic locking prevents race conditions in concurrent updates");
    console.log("4. attribute_exists and attribute_not_exists are useful for checking if attributes are present");
    console.log("5. Conditional operations are atomic - they either succeed completely or fail completely");
    console.log("6. You can use any valid comparison operators and functions in condition expressions");
    console.log("7. Conditional operations don't consume write capacity if the condition fails");
    
  } catch (error) {
    console.error("Error:", error);
  }
}
```
+ API の詳細については、「*AWS SDK for JavaScript API リファレンス*」の以下のトピックを参照してください。
  + [DeleteItem](https://docs.aws.amazon.com/AWSJavaScriptSDK/v3/latest/client/dynamodb/command/DeleteItemCommand)
  + [PutItem](https://docs.aws.amazon.com/AWSJavaScriptSDK/v3/latest/client/dynamodb/command/PutItemCommand)
  + [UpdateItem](https://docs.aws.amazon.com/AWSJavaScriptSDK/v3/latest/client/dynamodb/command/UpdateItemCommand)

### 式の属性名を使用する
<a name="dynamodb_Scenario_ExpressionAttributeNames_javascript_topic"></a>

次のコード例は、DynamoDB で式の属性名を使用する方法を示しています。
+ DynamoDB 式で予約語を操作します。
+ 式の属性名のプレースホルダーを使用します。
+ 属性名の特殊文字を処理します。

**SDK for JavaScript (v3)**  
を使用して式の属性名をデモンストレーションします AWS SDK for JavaScript。  

```
const { DynamoDBClient } = require("@aws-sdk/client-dynamodb");
const { 
  DynamoDBDocumentClient, 
  UpdateCommand,
  GetCommand,
  QueryCommand,
  ScanCommand
} = require("@aws-sdk/lib-dynamodb");

/**
 * Update an attribute that is a reserved word in DynamoDB.
 * 
 * This function demonstrates how to use expression attribute names to update
 * attributes that are reserved words in DynamoDB.
 * 
 * @param {Object} config - AWS configuration object
 * @param {string} tableName - The name of the DynamoDB table
 * @param {Object} key - The key of the item to update
 * @param {string} reservedWordAttribute - The reserved word attribute to update
 * @param {any} value - The value to set
 * @returns {Promise<Object>} - The response from DynamoDB
 */
async function updateReservedWordAttribute(
  config,
  tableName,
  key,
  reservedWordAttribute,
  value
) {
  // Initialize the DynamoDB client
  const client = new DynamoDBClient(config);
  const docClient = DynamoDBDocumentClient.from(client);
  
  // Define the update parameters using expression attribute names
  const params = {
    TableName: tableName,
    Key: key,
    UpdateExpression: "SET #attr = :value",
    ExpressionAttributeNames: {
      "#attr": reservedWordAttribute
    },
    ExpressionAttributeValues: {
      ":value": value
    },
    ReturnValues: "UPDATED_NEW"
  };
  
  // Perform the update operation
  const response = await docClient.send(new UpdateCommand(params));
  
  return response;
}

/**
 * Update an attribute that contains special characters.
 * 
 * This function demonstrates how to use expression attribute names to update
 * attributes that contain special characters.
 * 
 * @param {Object} config - AWS configuration object
 * @param {string} tableName - The name of the DynamoDB table
 * @param {Object} key - The key of the item to update
 * @param {string} specialCharAttribute - The attribute with special characters to update
 * @param {any} value - The value to set
 * @returns {Promise<Object>} - The response from DynamoDB
 */
async function updateSpecialCharacterAttribute(
  config,
  tableName,
  key,
  specialCharAttribute,
  value
) {
  // Initialize the DynamoDB client
  const client = new DynamoDBClient(config);
  const docClient = DynamoDBDocumentClient.from(client);
  
  // Define the update parameters using expression attribute names
  const params = {
    TableName: tableName,
    Key: key,
    UpdateExpression: "SET #attr = :value",
    ExpressionAttributeNames: {
      "#attr": specialCharAttribute
    },
    ExpressionAttributeValues: {
      ":value": value
    },
    ReturnValues: "UPDATED_NEW"
  };
  
  // Perform the update operation
  const response = await docClient.send(new UpdateCommand(params));
  
  return response;
}

/**
 * Query items using an attribute that is a reserved word.
 * 
 * This function demonstrates how to use expression attribute names in a query
 * when the attribute is a reserved word.
 * 
 * @param {Object} config - AWS configuration object
 * @param {string} tableName - The name of the DynamoDB table
 * @param {string} partitionKeyName - The name of the partition key attribute
 * @param {any} partitionKeyValue - The value of the partition key
 * @param {string} reservedWordAttribute - The reserved word attribute to filter on
 * @param {any} value - The value to compare against
 * @returns {Promise<Object>} - The response from DynamoDB
 */
async function queryWithReservedWordAttribute(
  config,
  tableName,
  partitionKeyName,
  partitionKeyValue,
  reservedWordAttribute,
  value
) {
  // Initialize the DynamoDB client
  const client = new DynamoDBClient(config);
  const docClient = DynamoDBDocumentClient.from(client);
  
  // Define the query parameters using expression attribute names
  const params = {
    TableName: tableName,
    KeyConditionExpression: "#pkName = :pkValue",
    FilterExpression: "#attr = :value",
    ExpressionAttributeNames: {
      "#pkName": partitionKeyName,
      "#attr": reservedWordAttribute
    },
    ExpressionAttributeValues: {
      ":pkValue": partitionKeyValue,
      ":value": value
    }
  };
  
  // Perform the query operation
  const response = await docClient.send(new QueryCommand(params));
  
  return response;
}

/**
 * Update a nested attribute with a path that contains reserved words.
 * 
 * This function demonstrates how to use expression attribute names to update
 * nested attributes where the path contains reserved words.
 * 
 * @param {Object} config - AWS configuration object
 * @param {string} tableName - The name of the DynamoDB table
 * @param {Object} key - The key of the item to update
 * @param {string[]} attributePath - The path to the nested attribute as an array
 * @param {any} value - The value to set
 * @returns {Promise<Object>} - The response from DynamoDB
 */
async function updateNestedReservedWordAttribute(
  config,
  tableName,
  key,
  attributePath,
  value
) {
  // Initialize the DynamoDB client
  const client = new DynamoDBClient(config);
  const docClient = DynamoDBDocumentClient.from(client);
  
  // Create expression attribute names for each part of the path
  const expressionAttributeNames = {};
  for (let i = 0; i < attributePath.length; i++) {
    expressionAttributeNames[`#attr${i}`] = attributePath[i];
  }
  
  // Build the attribute path using the expression attribute names
  const attributePathExpression = attributePath
    .map((_, i) => `#attr${i}`)
    .join(".");
  
  // Define the update parameters
  const params = {
    TableName: tableName,
    Key: key,
    UpdateExpression: `SET ${attributePathExpression} = :value`,
    ExpressionAttributeNames: expressionAttributeNames,
    ExpressionAttributeValues: {
      ":value": value
    },
    ReturnValues: "UPDATED_NEW"
  };
  
  // Perform the update operation
  const response = await docClient.send(new UpdateCommand(params));
  
  return response;
}

/**
 * Scan a table with multiple attribute name placeholders.
 * 
 * This function demonstrates how to use multiple expression attribute names
 * in a complex filter expression.
 * 
 * @param {Object} config - AWS configuration object
 * @param {string} tableName - The name of the DynamoDB table
 * @param {Object} filters - Object mapping attribute names to filter values
 * @returns {Promise<Object>} - The response from DynamoDB
 */
async function scanWithMultipleAttributeNames(
  config,
  tableName,
  filters
) {
  // Initialize the DynamoDB client
  const client = new DynamoDBClient(config);
  const docClient = DynamoDBDocumentClient.from(client);
  
  // Create expression attribute names and values
  const expressionAttributeNames = {};
  const expressionAttributeValues = {};
  const filterConditions = [];
  
  // Build the filter expression
  Object.entries(filters).forEach(([attrName, value], index) => {
    const nameKey = `#attr${index}`;
    const valueKey = `:val${index}`;
    
    expressionAttributeNames[nameKey] = attrName;
    expressionAttributeValues[valueKey] = value;
    filterConditions.push(`${nameKey} = ${valueKey}`);
  });
  
  // Join the filter conditions with AND
  const filterExpression = filterConditions.join(" AND ");
  
  // Define the scan parameters
  const params = {
    TableName: tableName,
    FilterExpression: filterExpression,
    ExpressionAttributeNames: expressionAttributeNames,
    ExpressionAttributeValues: expressionAttributeValues
  };
  
  // Perform the scan operation
  const response = await docClient.send(new ScanCommand(params));
  
  return response;
}

/**
 * Get the current value of an item.
 * 
 * Helper function to retrieve the current value of an item.
 * 
 * @param {Object} config - AWS configuration object
 * @param {string} tableName - The name of the DynamoDB table
 * @param {Object} key - The key of the item to get
 * @returns {Promise<Object|null>} - The item or null if not found
 */
async function getItem(
  config,
  tableName,
  key
) {
  // Initialize the DynamoDB client
  const client = new DynamoDBClient(config);
  const docClient = DynamoDBDocumentClient.from(client);
  
  // Define the get parameters
  const params = {
    TableName: tableName,
    Key: key
  };
  
  // Perform the get operation
  const response = await docClient.send(new GetCommand(params));
  
  // Return the item if it exists, otherwise null
  return response.Item || null;
}
```
を使用した式の属性名の使用例 AWS SDK for JavaScript。  

```
/**
 * Example of how to use expression attribute names.
 */
async function exampleUsage() {
  // Example parameters
  const config = { region: "us-west-2" };
  const tableName = "Products";
  const key = { ProductId: "P12345" };
  
  console.log("Demonstrating expression attribute names in DynamoDB");
  
  try {
    // Example 1: Update an attribute that is a reserved word
    console.log("\nExample 1: Updating an attribute that is a reserved word");
    const response1 = await updateReservedWordAttribute(
      config,
      tableName,
      key,
      "Size", // "SIZE" is a reserved word in DynamoDB
      "Large"
    );
    
    console.log("Updated attribute:", response1.Attributes);
    
    // Example 2: Update an attribute with special characters
    console.log("\nExample 2: Updating an attribute with special characters");
    const response2 = await updateSpecialCharacterAttribute(
      config,
      tableName,
      key,
      "Product-Type", // Contains a hyphen, which is a special character
      "Electronics"
    );
    
    console.log("Updated attribute:", response2.Attributes);
    
    // Example 3: Query with a reserved word attribute
    console.log("\nExample 3: Querying with a reserved word attribute");
    const response3 = await queryWithReservedWordAttribute(
      config,
      tableName,
      "Category",
      "Electronics",
      "Count", // "COUNT" is a reserved word in DynamoDB
      10
    );
    
    console.log(`Found ${response3.Items.length} items`);
    
    // Example 4: Update a nested attribute with reserved words in the path
    console.log("\nExample 4: Updating a nested attribute with reserved words in the path");
    const response4 = await updateNestedReservedWordAttribute(
      config,
      tableName,
      key,
      ["Dimensions", "Size", "Height"], // "SIZE" is a reserved word
      30
    );
    
    console.log("Updated nested attribute:", response4.Attributes);
    
    // Example 5: Scan with multiple attribute name placeholders
    console.log("\nExample 5: Scanning with multiple attribute name placeholders");
    const response5 = await scanWithMultipleAttributeNames(
      config,
      tableName,
      {
        "Size": "Large",
        "Count": 10,
        "Product-Type": "Electronics"
      }
    );
    
    console.log(`Found ${response5.Items.length} items`);
    
    // Get the final state of the item
    console.log("\nFinal state of the item:");
    const item = await getItem(config, tableName, key);
    console.log(JSON.stringify(item, null, 2));
    
    // Show some common reserved words
    console.log("\nSome common DynamoDB reserved words:");
    const commonReservedWords = [
      "ABORT", "ABSOLUTE", "ACTION", "ADD", "ALL", "ALTER", "AND", "ANY", "AS",
      "ASC", "BETWEEN", "BY", "CASE", "CAST", "COLUMN", "CONNECT", "COUNT",
      "CREATE", "CURRENT", "DATE", "DELETE", "DESC", "DROP", "ELSE", "EXISTS",
      "FOR", "FROM", "GRANT", "GROUP", "HAVING", "IN", "INDEX", "INSERT", "INTO",
      "IS", "JOIN", "KEY", "LEVEL", "LIKE", "LIMIT", "LOCAL", "MAX", "MIN", "NAME",
      "NOT", "NULL", "OF", "ON", "OR", "ORDER", "OUTER", "REPLACE", "RETURN",
      "SELECT", "SET", "SIZE", "TABLE", "THEN", "TO", "UPDATE", "USER", "VALUES",
      "VIEW", "WHERE"
    ];
    console.log(commonReservedWords.join(", "));
    
    // Explain expression attribute names
    console.log("\nKey points about expression attribute names:");
    console.log("1. Use expression attribute names (#name) for reserved words");
    console.log("2. Use expression attribute names for attributes with special characters");
    console.log("3. Special characters include: spaces, hyphens, dots, and other non-alphanumeric characters");
    console.log("4. Expression attribute names are required for nested attributes with reserved words");
    console.log("5. You can use multiple expression attribute names in a single expression");
    console.log("6. Expression attribute names are case-sensitive");
    console.log("7. Expression attribute names are only used in expressions, not in the actual data");
    
  } catch (error) {
    console.error("Error:", error);
  }
}
```
+ API の詳細については、「*AWS SDK for JavaScript API リファレンス*」の以下のトピックを参照してください。
  + [クエリ](https://docs.aws.amazon.com/AWSJavaScriptSDK/v3/latest/client/dynamodb/command/QueryCommand)
  + [UpdateItem](https://docs.aws.amazon.com/AWSJavaScriptSDK/v3/latest/client/dynamodb/command/UpdateItemCommand)

### スケジュールされたイベントを使用した Lambda 関数の呼び出し
<a name="cross_LambdaScheduledEvents_javascript_topic"></a>

次のコード例は、Amazon EventBridge スケジュールされたイベントによって呼び出される AWS Lambda 関数を作成する方法を示しています。

**SDK for JavaScript (v3)**  
 AWS Lambda 関数を呼び出す Amazon EventBridge スケジュールされたイベントを作成する方法を示します。cron 式を使用して Lambda 関数が呼び出されるタイミングをスケジュールするように EventBridge を設定します。この例では、Lambda JavaScript ランタイム API を使用して Lambda 関数を作成します。この例では、さまざまな AWS サービスを呼び出して、特定のユースケースを実行します。この例では、年間の記念日に従業員を祝福するモバイルテキストメッセージを従業員に送信するアプリを作成する方法を示します。  
 完全なソースコードとセットアップおよび実行の手順については、[GitHub](https://github.com/awsdocs/aws-doc-sdk-examples/tree/main/javascriptv3/example_code/cross-services/lambda-scheduled-events) で完全な例を参照してください。  
この例は、[AWS SDK for JavaScript v3 デベロッパーガイド](https://docs.aws.amazon.com/sdk-for-javascript/v3/developer-guide/scheduled-events-invoking-lambda-example.html)でも使用できます。  

**この例で使用されているサービス**
+ CloudWatch Logs
+ DynamoDB
+ EventBridge
+ Lambda
+ Amazon SNS

## サーバーレスサンプル
<a name="serverless_examples"></a>

### DynamoDB トリガーから Lambda 関数を呼び出す
<a name="serverless_DynamoDB_Lambda_javascript_topic"></a>

次のコード例は、DynamoDB ストリームからレコードを受信することによってトリガーされるイベントを受け取る、Lambda 関数の実装方法を示しています。関数は DynamoDB ペイロードを取得し、レコードの内容をログ記録します。

**SDK for JavaScript (v3)**  
 GitHub には、その他のリソースもあります。[サーバーレスサンプル](https://github.com/aws-samples/serverless-snippets/tree/main/integration-ddb-to-lambda)リポジトリで完全な例を見つけて、設定と実行の方法を確認してください。
JavaScript を使用した Lambda での DynamoDB イベントの消費。  

```
// Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
// SPDX-License-Identifier: Apache-2.0
exports.handler = async (event, context) => {
    console.log(JSON.stringify(event, null, 2));
    event.Records.forEach(record => {
        logDynamoDBRecord(record);
    });
};

const logDynamoDBRecord = (record) => {
    console.log(record.eventID);
    console.log(record.eventName);
    console.log(`DynamoDB Record: ${JSON.stringify(record.dynamodb)}`);
};
```
TypeScript を使用した Lambda での DynamoDB イベントの消費。  

```
export const handler = async (event, context) => {
    console.log(JSON.stringify(event, null, 2));
    event.Records.forEach(record => {
        logDynamoDBRecord(record);
    });
}
const logDynamoDBRecord = (record) => {
    console.log(record.eventID);
    console.log(record.eventName);
    console.log(`DynamoDB Record: ${JSON.stringify(record.dynamodb)}`);
};
```

### DynamoDB トリガーで Lambda 関数のバッチアイテムの失敗をレポートする
<a name="serverless_DynamoDB_Lambda_batch_item_failures_javascript_topic"></a>

次のコード例は、DynamoDB ストリームからイベントを受け取る Lambda 関数の部分的なバッチレスポンスの実装方法を示しています。この関数は、レスポンスとしてバッチアイテムの失敗を報告し、対象のメッセージを後で再試行するよう Lambda に伝えます。

**SDK for JavaScript (v3)**  
 GitHub には、その他のリソースもあります。[サーバーレスサンプル](https://github.com/aws-samples/serverless-snippets/tree/main/integration-ddb-to-lambda-with-batch-item-handling)リポジトリで完全な例を見つけて、設定と実行の方法を確認してください。
JavaScript を使用して Lambda で DynamoDB のバッチアイテム失敗のレポート。  

```
export const handler = async (event) => {
  const records = event.Records;
  let curRecordSequenceNumber = "";

  for (const record of records) {
    try {
      // Process your record
      curRecordSequenceNumber = record.dynamodb.SequenceNumber;
    } catch (e) {
      // Return failed record's sequence number
      return { batchItemFailures: [{ itemIdentifier: curRecordSequenceNumber }] };
    }
  }

  return { batchItemFailures: [] };
};
```
TypeScript を使用して Lambda で DynamoDB のバッチアイテム失敗をレポートする。  

```
import {
  DynamoDBBatchResponse,
  DynamoDBBatchItemFailure,
  DynamoDBStreamEvent,
} from "aws-lambda";

export const handler = async (
  event: DynamoDBStreamEvent
): Promise<DynamoDBBatchResponse> => {
  const batchItemFailures: DynamoDBBatchItemFailure[] = [];
  let curRecordSequenceNumber;

  for (const record of event.Records) {
    curRecordSequenceNumber = record.dynamodb?.SequenceNumber;

    if (curRecordSequenceNumber) {
      batchItemFailures.push({
        itemIdentifier: curRecordSequenceNumber,
      });
    }
  }

  return { batchItemFailures: batchItemFailures };
};
```