# Query DynamoDB data using PartiQL SELECT statements with an AWS SDK
<a name="example_dynamodb_PartiQLSelect_section"></a>

The following code example shows how to query data using PartiQL SELECT statements.

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#### [ JavaScript ]

**SDK for JavaScript (v3)**  
Query items from a DynamoDB table using PartiQL SELECT statements with 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");
};
```
+ For API details, see the following topics in *AWS SDK for JavaScript API Reference*.
  + [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)

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For a complete list of AWS SDK developer guides and code examples, see [Using DynamoDB with an AWS SDK](sdk-general-information-section.md). This topic also includes information about getting started and details about previous SDK versions.