# Perform set operations in DynamoDB with an AWS SDK
<a name="example_dynamodb_Scenario_SetOperations_section"></a>

The following code examples show how to perform set operations in DynamoDB.
+ Add elements to a set attribute.
+ Remove elements from a set attribute.
+ Use ADD and DELETE operations with sets.

------
#### [ Java ]

**SDK for Java 2.x**  
Demonstrate set operations using AWS SDK for Java 2.x.  

```
import software.amazon.awssdk.services.dynamodb.DynamoDbClient;
import software.amazon.awssdk.services.dynamodb.model.AttributeValue;
import software.amazon.awssdk.services.dynamodb.model.DynamoDbException;
import software.amazon.awssdk.services.dynamodb.model.GetItemRequest;
import software.amazon.awssdk.services.dynamodb.model.GetItemResponse;
import software.amazon.awssdk.services.dynamodb.model.ReturnValue;
import software.amazon.awssdk.services.dynamodb.model.UpdateItemRequest;
import software.amazon.awssdk.services.dynamodb.model.UpdateItemResponse;

import java.util.HashMap;
import java.util.HashSet;
import java.util.Map;
import java.util.Set;

    /**
     * Adds values to a string set attribute.
     *
     * <p>This method demonstrates how to use the ADD operation to add values
     * to a string set attribute.
     *
     * @param dynamoDbClient The DynamoDB client
     * @param tableName The name of the DynamoDB table
     * @param key The key of the item to update
     * @param setAttributeName The name of the set attribute
     * @param valuesToAdd The values to add to the set
     * @return The response from DynamoDB
     * @throws DynamoDbException if an error occurs during the operation
     */
    public static UpdateItemResponse addToStringSet(
        DynamoDbClient dynamoDbClient,
        String tableName,
        Map<String, AttributeValue> key,
        String setAttributeName,
        Set<String> valuesToAdd) {

        // Create a string set value from the values to add
        AttributeValue setValue = AttributeValue.builder().ss(valuesToAdd).build();

        // Define the update parameters
        UpdateItemRequest request = UpdateItemRequest.builder()
            .tableName(tableName)
            .key(key)
            .updateExpression("ADD #setAttr :valuesToAdd")
            .expressionAttributeNames(Map.of("#setAttr", setAttributeName))
            .expressionAttributeValues(Map.of(":valuesToAdd", setValue))
            .returnValues(ReturnValue.UPDATED_NEW)
            .build();

        // Perform the update operation
        return dynamoDbClient.updateItem(request);
    }

    /**
     * Adds values to a number set attribute.
     *
     * <p>This method demonstrates how to use the ADD operation to add values
     * to a number set attribute.
     *
     * @param dynamoDbClient The DynamoDB client
     * @param tableName The name of the DynamoDB table
     * @param key The key of the item to update
     * @param setAttributeName The name of the set attribute
     * @param valuesToAdd The values to add to the set
     * @return The response from DynamoDB
     * @throws DynamoDbException if an error occurs during the operation
     */
    public static UpdateItemResponse addToNumberSet(
        DynamoDbClient dynamoDbClient,
        String tableName,
        Map<String, AttributeValue> key,
        String setAttributeName,
        Set<Number> valuesToAdd) {

        // Convert numbers to strings for DynamoDB
        Set<String> stringValues = new HashSet<>();
        for (Number value : valuesToAdd) {
            stringValues.add(value.toString());
        }

        // Create a number set value from the values to add
        AttributeValue setValue = AttributeValue.builder().ns(stringValues).build();

        // Define the update parameters
        UpdateItemRequest request = UpdateItemRequest.builder()
            .tableName(tableName)
            .key(key)
            .updateExpression("ADD #setAttr :valuesToAdd")
            .expressionAttributeNames(Map.of("#setAttr", setAttributeName))
            .expressionAttributeValues(Map.of(":valuesToAdd", setValue))
            .returnValues(ReturnValue.UPDATED_NEW)
            .build();

        // Perform the update operation
        return dynamoDbClient.updateItem(request);
    }

    /**
     * Removes values from a set attribute.
     *
     * <p>This method demonstrates how to use the DELETE operation to remove values
     * from a set attribute.
     *
     * @param dynamoDbClient The DynamoDB client
     * @param tableName The name of the DynamoDB table
     * @param key The key of the item to update
     * @param setAttributeName The name of the set attribute
     * @param valuesToRemove The values to remove from the set
     * @param isNumberSet Whether the set is a number set (true) or string set (false)
     * @return The response from DynamoDB
     * @throws DynamoDbException if an error occurs during the operation
     */
    public static UpdateItemResponse removeFromSet(
        DynamoDbClient dynamoDbClient,
        String tableName,
        Map<String, AttributeValue> key,
        String setAttributeName,
        Set<?> valuesToRemove,
        boolean isNumberSet) {

        AttributeValue setValue;

        if (isNumberSet) {
            // Convert numbers to strings for DynamoDB
            Set<String> stringValues = new HashSet<>();
            for (Object value : valuesToRemove) {
                if (value instanceof Number) {
                    stringValues.add(value.toString());
                } else {
                    throw new IllegalArgumentException("Values must be numbers for a number set");
                }
            }

            setValue = AttributeValue.builder().ns(stringValues).build();
        } else {
            // Convert objects to strings for DynamoDB
            Set<String> stringValues = new HashSet<>();
            for (Object value : valuesToRemove) {
                stringValues.add(value.toString());
            }

            setValue = AttributeValue.builder().ss(stringValues).build();
        }

        // Define the update parameters
        UpdateItemRequest request = UpdateItemRequest.builder()
            .tableName(tableName)
            .key(key)
            .updateExpression("DELETE #setAttr :valuesToRemove")
            .expressionAttributeNames(Map.of("#setAttr", setAttributeName))
            .expressionAttributeValues(Map.of(":valuesToRemove", setValue))
            .returnValues(ReturnValue.UPDATED_NEW)
            .build();

        // Perform the update operation
        return dynamoDbClient.updateItem(request);
    }

    /**
     * Checks if a value exists in a set attribute.
     *
     * <p>This method demonstrates how to use the contains function to check
     * if a value exists in a set attribute.
     *
     * @param dynamoDbClient The DynamoDB client
     * @param tableName The name of the DynamoDB table
     * @param key The key of the item to check
     * @param setAttributeName The name of the set attribute
     * @param valueToCheck The value to check for
     * @return Map containing the result of the check
     * @throws DynamoDbException if an error occurs during the operation
     */
    public static Map<String, Object> checkIfValueInSet(
        DynamoDbClient dynamoDbClient,
        String tableName,
        Map<String, AttributeValue> key,
        String setAttributeName,
        String valueToCheck) {

        Map<String, Object> result = new HashMap<>();

        try {
            // Define the update parameters with a condition expression
            UpdateItemRequest request = UpdateItemRequest.builder()
                .tableName(tableName)
                .key(key)
                .updateExpression("SET #tempAttr = :tempVal")
                .conditionExpression("contains(#setAttr, :valueToCheck)")
                .expressionAttributeNames(Map.of("#setAttr", setAttributeName, "#tempAttr", "TempAttribute"))
                .expressionAttributeValues(Map.of(
                    ":valueToCheck", AttributeValue.builder().s(valueToCheck).build(),
                    ":tempVal", AttributeValue.builder().s("TempValue").build()))
                .returnValues(ReturnValue.UPDATED_NEW)
                .build();

            // Attempt the update operation
            dynamoDbClient.updateItem(request);

            // If we get here, the condition was met
            result.put("exists", true);
            result.put("message", "Value '" + valueToCheck + "' exists in the set");

            // Clean up the temporary attribute
            UpdateItemRequest cleanupRequest = UpdateItemRequest.builder()
                .tableName(tableName)
                .key(key)
                .updateExpression("REMOVE #tempAttr")
                .expressionAttributeNames(Map.of("#tempAttr", "TempAttribute"))
                .build();

            dynamoDbClient.updateItem(cleanupRequest);

        } catch (DynamoDbException e) {
            if (e.getMessage().contains("ConditionalCheckFailed")) {
                // The condition was not met
                result.put("exists", false);
                result.put("message", "Value '" + valueToCheck + "' does not exist in the set");
            } else {
                // Some other error occurred
                result.put("exists", false);
                result.put("message", "Error checking set: " + e.getMessage());
                result.put("error", e.getClass().getSimpleName());
            }
        }

        return result;
    }

    /**
     * Creates a set with multiple values in a single operation.
     *
     * <p>This method demonstrates how to create a set with multiple values
     * in a single update operation.
     *
     * @param dynamoDbClient The DynamoDB client
     * @param tableName The name of the DynamoDB table
     * @param key The key of the item to update
     * @param setAttributeName The name of the set attribute
     * @param setValues The values to include in the set
     * @param isNumberSet Whether to create a number set (true) or string set (false)
     * @return The response from DynamoDB
     * @throws DynamoDbException if an error occurs during the operation
     */
    public static UpdateItemResponse createSetWithValues(
        DynamoDbClient dynamoDbClient,
        String tableName,
        Map<String, AttributeValue> key,
        String setAttributeName,
        Set<?> setValues,
        boolean isNumberSet) {

        AttributeValue setValue;

        if (isNumberSet) {
            // Convert numbers to strings for DynamoDB
            Set<String> stringValues = new HashSet<>();
            for (Object value : setValues) {
                if (value instanceof Number) {
                    stringValues.add(value.toString());
                } else {
                    throw new IllegalArgumentException("Values must be numbers for a number set");
                }
            }

            setValue = AttributeValue.builder().ns(stringValues).build();
        } else {
            // Convert objects to strings for DynamoDB
            Set<String> stringValues = new HashSet<>();
            for (Object value : setValues) {
                stringValues.add(value.toString());
            }

            setValue = AttributeValue.builder().ss(stringValues).build();
        }

        // Define the update parameters
        UpdateItemRequest request = UpdateItemRequest.builder()
            .tableName(tableName)
            .key(key)
            .updateExpression("SET #setAttr = :setValue")
            .expressionAttributeNames(Map.of("#setAttr", setAttributeName))
            .expressionAttributeValues(Map.of(":setValue", setValue))
            .returnValues(ReturnValue.UPDATED_NEW)
            .build();

        // Perform the update operation
        return dynamoDbClient.updateItem(request);
    }

    /**
     * Gets the current value of a set attribute.
     *
     * <p>Helper method to retrieve the current value of a set attribute.
     *
     * @param dynamoDbClient The DynamoDB client
     * @param tableName The name of the DynamoDB table
     * @param key The key of the item to get
     * @param setAttributeName The name of the set attribute
     * @return The set attribute value or null if not found
     * @throws DynamoDbException if an error occurs during the operation
     */
    public static AttributeValue getSetAttribute(
        DynamoDbClient dynamoDbClient, String tableName, Map<String, AttributeValue> key, String setAttributeName) {

        // Define the get parameters
        GetItemRequest request = GetItemRequest.builder()
            .tableName(tableName)
            .key(key)
            .projectionExpression(setAttributeName)
            .build();

        try {
            // Perform the get operation
            GetItemResponse response = dynamoDbClient.getItem(request);

            // Return the set attribute if it exists, otherwise null
            if (response.item() != null && response.item().containsKey(setAttributeName)) {
                return response.item().get(setAttributeName);
            }

            return null;
        } catch (DynamoDbException e) {
            throw DynamoDbException.builder()
                .message("Failed to get set attribute: " + e.getMessage())
                .cause(e)
                .build();
        }
    }
```
Example usage of set operations with AWS SDK for Java 2.x.  

```
    public static void exampleUsage(DynamoDbClient dynamoDbClient, String tableName) {
        // Example key
        Map<String, AttributeValue> key = new HashMap<>();
        key.put("ProductId", AttributeValue.builder().s("P12345").build());

        System.out.println("Demonstrating set operations in DynamoDB");

        try {
            // Example 1: Create a string set with multiple values
            System.out.println("\nExample 1: Creating a string set with multiple values");
            Set<String> tags = new HashSet<>();
            tags.add("Electronics");
            tags.add("Gadget");
            tags.add("Smartphone");

            UpdateItemResponse createResponse = createSetWithValues(
                dynamoDbClient, tableName, key, "Tags", tags, false // Not a number set
                );

            System.out.println("Created set attribute: " + createResponse.attributes());

            // Example 2: Add values to a string set
            System.out.println("\nExample 2: Adding values to a string set");
            Set<String> additionalTags = new HashSet<>();
            additionalTags.add("Mobile");
            additionalTags.add("Wireless");

            UpdateItemResponse addResponse = addToStringSet(dynamoDbClient, tableName, key, "Tags", additionalTags);

            System.out.println("Updated set attribute: " + addResponse.attributes());

            // Example 3: Create a number set with multiple values
            System.out.println("\nExample 3: Creating a number set with multiple values");
            Set<Number> ratings = new HashSet<>();
            ratings.add(4);
            ratings.add(5);
            ratings.add(4.5);

            UpdateItemResponse createNumberSetResponse = createSetWithValues(
                dynamoDbClient, tableName, key, "Ratings", ratings, true // Is a number set
                );

            System.out.println("Created number set attribute: " + createNumberSetResponse.attributes());

            // Example 4: Add values to a number set
            System.out.println("\nExample 4: Adding values to a number set");
            Set<Number> additionalRatings = new HashSet<>();
            additionalRatings.add(3.5);
            additionalRatings.add(4.2);

            UpdateItemResponse addNumberResponse =
                addToNumberSet(dynamoDbClient, tableName, key, "Ratings", additionalRatings);

            System.out.println("Updated number set attribute: " + addNumberResponse.attributes());

            // Example 5: Remove values from a set
            System.out.println("\nExample 5: Removing values from a set");
            Set<String> tagsToRemove = new HashSet<>();
            tagsToRemove.add("Gadget");

            UpdateItemResponse removeResponse = removeFromSet(
                dynamoDbClient, tableName, key, "Tags", tagsToRemove, false // Not a number set
                );

            System.out.println("Updated set after removal: " + removeResponse.attributes());

            // Example 6: Check if a value exists in a set
            System.out.println("\nExample 6: Checking if a value exists in a set");
            Map<String, Object> checkResult = checkIfValueInSet(dynamoDbClient, tableName, key, "Tags", "Electronics");

            System.out.println("Check result: " + checkResult.get("message"));

            // Example 7: Get the current value of a set attribute
            System.out.println("\nExample 7: Getting the current value of a set attribute");
            AttributeValue currentStringSet = getSetAttribute(dynamoDbClient, tableName, key, "Tags");

            if (currentStringSet != null && currentStringSet.ss() != null) {
                System.out.println("Current string set values: " + currentStringSet.ss());
            } else {
                System.out.println("String set attribute not found");
            }

            AttributeValue currentNumberSet = getSetAttribute(dynamoDbClient, tableName, key, "Ratings");

            if (currentNumberSet != null && currentNumberSet.ns() != null) {
                System.out.println("Current number set values: " + currentNumberSet.ns());
            } else {
                System.out.println("Number set attribute not found");
            }

            // Explain set operations
            System.out.println("\nKey points about DynamoDB set operations:");
            System.out.println(
                "1. DynamoDB supports three set types: string sets (SS), number sets (NS), and binary sets (BS)");
            System.out.println("2. Sets can only contain elements of the same type");
            System.out.println("3. Use ADD to add elements to a set");
            System.out.println("4. Use DELETE to remove elements from a set");
            System.out.println("5. Sets automatically remove duplicate values");
            System.out.println("6. Sets are unordered collections");
            System.out.println("7. Use the contains function to check if a value exists in a set");
            System.out.println("8. You can create a set with multiple values in a single operation");

        } catch (DynamoDbException e) {
            System.err.println("Error: " + e.getMessage());
            e.printStackTrace();
        }
    }
```
+  For API details, see [UpdateItem](https://docs.aws.amazon.com/goto/SdkForJavaV2/dynamodb-2012-08-10/UpdateItem) in *AWS SDK for Java 2.x API Reference*. 

------
#### [ JavaScript ]

**SDK for JavaScript (v3)**  
Demonstrate set operations using 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;
}
```
Example usage of set operations with 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);
  }
}
```
+  For API details, see [UpdateItem](https://docs.aws.amazon.com/AWSJavaScriptSDK/v3/latest/client/dynamodb/command/UpdateItemCommand) in *AWS SDK for JavaScript API Reference*. 

------
#### [ Python ]

**SDK for Python (Boto3)**  
Demonstrate set operations using AWS SDK for Python (Boto3).  

```
import boto3
from typing import Any, Dict, List


def create_set_attribute(
    table_name: str,
    key: Dict[str, Any],
    set_name: str,
    set_values: List[Any],
    set_type: str = "string",
) -> Dict[str, Any]:
    """
    Create a new set attribute or add elements to an existing set.

    This function demonstrates how to use the ADD operation to create a new set
    or add elements to an existing set.

    Args:
        table_name (str): The name of the DynamoDB table.
        key (Dict[str, Any]): The primary key of the item to update.
        set_name (str): The name of the set attribute.
        set_values (List[Any]): The values to add to the set.
        set_type (str, optional): The type of set to create: "string", "number", or "binary".
            Defaults to "string".

    Returns:
        Dict[str, Any]: The response from DynamoDB containing the updated attribute values.
    """
    # Initialize the DynamoDB resource
    dynamodb = boto3.resource("dynamodb")
    table = dynamodb.Table(table_name)

    # Convert the list to a DynamoDB set based on the specified type
    if set_type == "string":
        dynamo_set = set(str(value) for value in set_values)
    elif set_type == "number":
        # We need to use actual float values for the DynamoDB API
        # but mypy expects strings in sets, so we need to use type: ignore
        dynamo_set = set(float(value) for value in set_values)  # type: ignore
    else:  # binary set is not directly supported in high-level API, handled differently
        raise ValueError("Binary sets are not supported in this example")

    # Use the ADD operation to create or update the set
    response = table.update_item(
        Key=key,
        UpdateExpression="ADD #set_attr :set_values",
        ExpressionAttributeNames={"#set_attr": set_name},
        ExpressionAttributeValues={":set_values": dynamo_set},
        ReturnValues="UPDATED_NEW",
    )

    return response


def add_to_set(
    table_name: str, key: Dict[str, Any], set_name: str, values_to_add: List[Any]
) -> Dict[str, Any]:
    """
    Add elements to an existing set attribute.

    This function demonstrates how to use the ADD operation to add elements to an existing set.
    If the set doesn't exist, it will be created.

    Args:
        table_name (str): The name of the DynamoDB table.
        key (Dict[str, Any]): The primary key of the item to update.
        set_name (str): The name of the set attribute.
        values_to_add (List[Any]): The values to add to the set.

    Returns:
        Dict[str, Any]: The response from DynamoDB containing the updated attribute values.
    """
    # Initialize the DynamoDB resource
    dynamodb = boto3.resource("dynamodb")
    table = dynamodb.Table(table_name)

    # Convert the list to a set (assuming string set for simplicity)
    dynamo_set = set(str(value) for value in values_to_add)

    # Use the ADD operation to add values to the set
    response = table.update_item(
        Key=key,
        UpdateExpression="ADD #set_attr :values_to_add",
        ExpressionAttributeNames={"#set_attr": set_name},
        ExpressionAttributeValues={":values_to_add": dynamo_set},
        ReturnValues="UPDATED_NEW",
    )

    return response


def remove_from_set(
    table_name: str, key: Dict[str, Any], set_name: str, values_to_remove: List[Any]
) -> Dict[str, Any]:
    """
    Remove elements from a set attribute.

    This function demonstrates how to use the DELETE operation to remove elements from a set.
    If the last element is removed, the attribute will be deleted entirely.

    Args:
        table_name (str): The name of the DynamoDB table.
        key (Dict[str, Any]): The primary key of the item to update.
        set_name (str): The name of the set attribute.
        values_to_remove (List[Any]): The values to remove from the set.

    Returns:
        Dict[str, Any]: The response from DynamoDB containing the updated attribute values.
    """
    # Initialize the DynamoDB resource
    dynamodb = boto3.resource("dynamodb")
    table = dynamodb.Table(table_name)

    # Convert the list to a set (assuming string set for simplicity)
    dynamo_set = set(str(value) for value in values_to_remove)

    # Use the DELETE operation to remove values from the set
    response = table.update_item(
        Key=key,
        UpdateExpression="DELETE #set_attr :values_to_remove",
        ExpressionAttributeNames={"#set_attr": set_name},
        ExpressionAttributeValues={":values_to_remove": dynamo_set},
        ReturnValues="UPDATED_NEW",
    )

    return response


def check_if_set_exists(table_name: str, key: Dict[str, Any], set_name: str) -> bool:
    """
    Check if a set attribute exists in an item.

    This function demonstrates how to check if a set attribute exists after
    potentially removing all elements from it.

    Args:
        table_name (str): The name of the DynamoDB table.
        key (Dict[str, Any]): The primary key of the item to check.
        set_name (str): The name of the set attribute.

    Returns:
        bool: True if the set attribute exists, False otherwise.
    """
    # Initialize the DynamoDB resource
    dynamodb = boto3.resource("dynamodb")
    table = dynamodb.Table(table_name)

    # Get the item
    response = table.get_item(
        Key=key, ProjectionExpression="#set_attr", ExpressionAttributeNames={"#set_attr": set_name}
    )

    # Check if the item exists and has the set attribute
    return "Item" in response and set_name in response["Item"]


def demonstrate_last_element_removal(
    table_name: str, key: Dict[str, Any], set_name: str
) -> Dict[str, Any]:
    """
    Demonstrate what happens when you remove the last element from a set.

    This function creates a set with a single element, then removes that element,
    showing that the attribute is completely removed when the last element is deleted.

    Args:
        table_name (str): The name of the DynamoDB table.
        key (Dict[str, Any]): The primary key of the item to update.
        set_name (str): The name of the set attribute.

    Returns:
        Dict[str, Any]: A dictionary containing the results of the demonstration.
    """
    # Step 1: Create a set with a single element
    create_response = create_set_attribute(
        table_name=table_name,
        key=key,
        set_name=set_name,
        set_values=["last_element"],
        set_type="string",
    )

    # Step 2: Check that the set exists
    exists_before = check_if_set_exists(table_name, key, set_name)

    # Step 3: Remove the last element
    delete_response = remove_from_set(
        table_name=table_name, key=key, set_name=set_name, values_to_remove=["last_element"]
    )

    # Step 4: Check if the set still exists
    exists_after = check_if_set_exists(table_name, key, set_name)

    # Return the results
    return {
        "create_response": create_response,
        "exists_before": exists_before,
        "delete_response": delete_response,
        "exists_after": exists_after,
    }


def work_with_number_set(
    table_name: str,
    key: Dict[str, Any],
    set_name: str,
    initial_values: List[float],
    values_to_add: List[float],
    values_to_remove: List[float],
) -> Dict[str, Any]:
    """
    Demonstrate working with a number set in DynamoDB.

    This function shows how to create and manipulate a set of numbers.

    Args:
        table_name (str): The name of the DynamoDB table.
        key (Dict[str, Any]): The primary key of the item to update.
        set_name (str): The name of the set attribute.
        initial_values (List[float]): The initial values for the set.
        values_to_add (List[float]): Values to add to the set.
        values_to_remove (List[float]): Values to remove from the set.

    Returns:
        Dict[str, Any]: A dictionary containing the responses from each operation.
    """
    # Step 1: Create the number set
    create_response = create_set_attribute(
        table_name=table_name,
        key=key,
        set_name=set_name,
        set_values=initial_values,
        set_type="number",
    )

    # Step 2: Add more numbers to the set
    add_response = add_to_set(
        table_name=table_name, key=key, set_name=set_name, values_to_add=values_to_add
    )

    # Step 3: Remove some numbers from the set
    remove_response = remove_from_set(
        table_name=table_name, key=key, set_name=set_name, values_to_remove=values_to_remove
    )

    # Step 4: Get the final state
    dynamodb = boto3.resource("dynamodb")
    table = dynamodb.Table(table_name)

    get_response = table.get_item(
        Key=key,
        ProjectionExpression=f"#{set_name}",
        ExpressionAttributeNames={f"#{set_name}": set_name},
    )

    # Return all responses
    return {
        "create_response": create_response,
        "add_response": add_response,
        "remove_response": remove_response,
        "final_state": get_response.get("Item", {}),
    }
```
Example usage of set operations with AWS SDK for Python (Boto3).  

```
def example_usage():
    """Example of how to use the set operations functions."""
    # Example parameters
    table_name = "UserPreferences"
    key = {"UserId": "user123"}

    print("Example 1: Creating a string set attribute")
    try:
        response = create_set_attribute(
            table_name=table_name,
            key=key,
            set_name="FavoriteTags",
            set_values=["AWS", "DynamoDB", "NoSQL"],
            set_type="string",
        )
        print(f"Set attribute created successfully: {response.get('Attributes', {})}")
    except Exception as e:
        print(f"Error creating set attribute: {e}")

    print("\nExample 2: Adding elements to an existing set")
    try:
        response = add_to_set(
            table_name=table_name,
            key=key,
            set_name="FavoriteTags",
            values_to_add=["Database", "Serverless"],
        )
        print(f"Elements added to set successfully: {response.get('Attributes', {})}")
    except Exception as e:
        print(f"Error adding to set: {e}")

    print("\nExample 3: Removing elements from a set")
    try:
        response = remove_from_set(
            table_name=table_name, key=key, set_name="FavoriteTags", values_to_remove=["NoSQL"]
        )
        print(f"Elements removed from set successfully: {response.get('Attributes', {})}")
    except Exception as e:
        print(f"Error removing from set: {e}")

    print("\nExample 4: Demonstrating what happens when you remove the last element from a set")
    try:
        results = demonstrate_last_element_removal(
            table_name=table_name, key={"UserId": "tempUser"}, set_name="SingleElementSet"
        )

        print(f"Set exists before removal: {results['exists_before']}")
        print(f"Set exists after removal: {results['exists_after']}")

        if not results["exists_after"]:
            print("The set attribute was completely removed when the last element was deleted.")
        else:
            print("The set attribute still exists after removing the last element.")
    except Exception as e:
        print(f"Error in last element removal demonstration: {e}")

    print("\nExample 5: Working with a number set")
    try:
        results = work_with_number_set(
            table_name=table_name,
            key={"UserId": "user456"},
            set_name="LuckyNumbers",
            initial_values=[7, 13, 42],
            values_to_add=[99, 100],
            values_to_remove=[13],
        )

        print(f"Initial number set: {results['create_response'].get('Attributes', {})}")
        print(f"After adding numbers: {results['add_response'].get('Attributes', {})}")
        print(f"After removing numbers: {results['remove_response'].get('Attributes', {})}")
        print(f"Final state: {results['final_state']}")
    except Exception as e:
        print(f"Error working with number set: {e}")

    print("\nKey Points About DynamoDB Sets:")
    print("1. Sets can only contain elements of the same type (string, number, or binary)")
    print("2. Sets automatically eliminate duplicate values")
    print("3. The ADD operation creates a set if it doesn't exist")
    print("4. The DELETE operation removes specified elements from a set")
    print("5. When the last element is removed from a set, the entire attribute is deleted")
    print("6. Empty sets are not allowed in DynamoDB")
    print("7. Sets are unordered collections")
    print("8. The ADD operation is atomic for sets")
```
+  For API details, see [UpdateItem](https://docs.aws.amazon.com/goto/boto3/dynamodb-2012-08-10/UpdateItem) in *AWS SDK for Python (Boto3) API Reference*. 

------

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.