# AWS SDK を使用して、DynamoDB で複数の値を 1 つの属性と比較する
<a name="example_dynamodb_Scenario_CompareMultipleValues_section"></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。

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

**SDK for Java 2.x**  
AWS SDK for Java 2.x を使用して、複数の値を DynamoDB の 1 つの属性と比較します。  

```
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.QueryRequest;
import software.amazon.awssdk.services.dynamodb.model.QueryResponse;
import software.amazon.awssdk.services.dynamodb.model.ScanRequest;
import software.amazon.awssdk.services.dynamodb.model.ScanResponse;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Locale;
import java.util.Map;

    /**
     * Queries a table using the IN operator to compare multiple values with a single attribute.
     *
     * <p>This method demonstrates how to use the IN operator in a filter expression
     * to match an attribute against multiple values.
     *
     * @param dynamoDbClient The DynamoDB client
     * @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 to query
     * @param attributeName The name of the attribute to compare
     * @param valuesList List of values to compare against
     * @return The query response from DynamoDB
     * @throws DynamoDbException if an error occurs during the operation
     */
    public static QueryResponse compareMultipleValues(
        DynamoDbClient dynamoDbClient,
        String tableName,
        String partitionKeyName,
        AttributeValue partitionKeyValue,
        String attributeName,
        List<AttributeValue> valuesList) {

        // Create expression attribute names
        Map<String, String> expressionAttributeNames = new HashMap<>();
        expressionAttributeNames.put("#pkName", partitionKeyName);
        expressionAttributeNames.put("#attrName", attributeName);

        // Create expression attribute values
        Map<String, AttributeValue> expressionAttributeValues = new HashMap<>();
        expressionAttributeValues.put(":pkValue", partitionKeyValue);

        // Add values for IN operator
        for (int i = 0; i < valuesList.size(); i++) {
            expressionAttributeValues.put(":val" + i, valuesList.get(i));
        }

        // Build the IN clause
        StringBuilder inClause = new StringBuilder();
        for (int i = 0; i < valuesList.size(); i++) {
            if (i > 0) {
                inClause.append(", ");
            }
            inClause.append(":val").append(i);
        }

        // Define the query parameters
        QueryRequest request = QueryRequest.builder()
            .tableName(tableName)
            .keyConditionExpression("#pkName = :pkValue")
            .filterExpression("#attrName IN (" + inClause.toString() + ")")
            .expressionAttributeNames(expressionAttributeNames)
            .expressionAttributeValues(expressionAttributeValues)
            .build();

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

    /**
     * Queries a table using multiple OR conditions to compare multiple values with a single attribute.
     *
     * <p>This method demonstrates the alternative approach to using the IN operator,
     * by using multiple OR conditions.
     *
     * @param dynamoDbClient The DynamoDB client
     * @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 to query
     * @param attributeName The name of the attribute to compare
     * @param valuesList List of values to compare against
     * @return The query response from DynamoDB
     * @throws DynamoDbException if an error occurs during the operation
     */
    public static QueryResponse compareWithOrConditions(
        DynamoDbClient dynamoDbClient,
        String tableName,
        String partitionKeyName,
        AttributeValue partitionKeyValue,
        String attributeName,
        List<AttributeValue> valuesList) {

        // Create expression attribute names
        Map<String, String> expressionAttributeNames = new HashMap<>();
        expressionAttributeNames.put("#pkName", partitionKeyName);
        expressionAttributeNames.put("#attrName", attributeName);

        // Create expression attribute values
        Map<String, AttributeValue> expressionAttributeValues = new HashMap<>();
        expressionAttributeValues.put(":pkValue", partitionKeyValue);

        // Add values for OR conditions
        for (int i = 0; i < valuesList.size(); i++) {
            expressionAttributeValues.put(":val" + i, valuesList.get(i));
        }

        // Build the OR conditions
        StringBuilder orConditions = new StringBuilder();
        for (int i = 0; i < valuesList.size(); i++) {
            if (i > 0) {
                orConditions.append(" OR ");
            }
            orConditions.append("#attrName = :val").append(i);
        }

        // Define the query parameters
        QueryRequest request = QueryRequest.builder()
            .tableName(tableName)
            .keyConditionExpression("#pkName = :pkValue")
            .filterExpression(orConditions.toString())
            .expressionAttributeNames(expressionAttributeNames)
            .expressionAttributeValues(expressionAttributeValues)
            .build();

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

    /**
     * Compares the performance of using the IN operator versus multiple OR conditions.
     *
     * <p>This method demonstrates the performance difference between using the IN operator
     * and using multiple OR conditions.
     *
     * @param dynamoDbClient The DynamoDB client
     * @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 to query
     * @param attributeName The name of the attribute to compare
     * @param valuesList List of values to compare against
     * @return Map containing the performance comparison results
     */
    public static Map<String, Object> comparePerformance(
        DynamoDbClient dynamoDbClient,
        String tableName,
        String partitionKeyName,
        AttributeValue partitionKeyValue,
        String attributeName,
        List<AttributeValue> valuesList) {

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

        try {
            // Measure performance of IN operator
            long inStartTime = System.nanoTime();
            QueryResponse inResponse = compareMultipleValues(
                dynamoDbClient, tableName, partitionKeyName, partitionKeyValue, attributeName, valuesList);
            long inEndTime = System.nanoTime();
            long inDuration = inEndTime - inStartTime;

            // Measure performance of OR conditions
            long orStartTime = System.nanoTime();
            QueryResponse orResponse = compareWithOrConditions(
                dynamoDbClient, tableName, partitionKeyName, partitionKeyValue, attributeName, valuesList);
            long orEndTime = System.nanoTime();
            long orDuration = orEndTime - orStartTime;

            // Record results
            results.put("inOperatorDuration", inDuration);
            results.put("orConditionsDuration", orDuration);
            results.put("inOperatorItems", inResponse.count());
            results.put("orConditionsItems", orResponse.count());
            results.put("inOperatorExpression", "IN operator with " + valuesList.size() + " values");
            results.put("orConditionsExpression", valuesList.size() + " OR conditions");
            results.put("success", true);

        } catch (DynamoDbException e) {
            results.put("success", false);
            results.put("error", e.getMessage());
        }

        return results;
    }

    /**
     * Scans a table using the IN operator with a large number of values.
     *
     * <p>This method demonstrates how to use the IN operator with a large number of values,
     * which can help stay within the 300 operator limit.
     *
     * @param dynamoDbClient The DynamoDB client
     * @param tableName The name of the DynamoDB table
     * @param attributeName The name of the attribute to compare
     * @param valuesList List of values to compare against
     * @return The scan response from DynamoDB
     * @throws DynamoDbException if an error occurs during the operation
     */
    public static ScanResponse scanWithLargeInClause(
        DynamoDbClient dynamoDbClient, String tableName, String attributeName, List<AttributeValue> valuesList) {

        // Create expression attribute names
        Map<String, String> expressionAttributeNames = new HashMap<>();
        expressionAttributeNames.put("#attrName", attributeName);

        // Create expression attribute values
        Map<String, AttributeValue> expressionAttributeValues = new HashMap<>();

        // Add values for IN operator
        for (int i = 0; i < valuesList.size(); i++) {
            expressionAttributeValues.put(":val" + i, valuesList.get(i));
        }

        // Build the IN clause
        StringBuilder inClause = new StringBuilder();
        for (int i = 0; i < valuesList.size(); i++) {
            if (i > 0) {
                inClause.append(", ");
            }
            inClause.append(":val").append(i);
        }

        // Define the scan parameters
        ScanRequest request = ScanRequest.builder()
            .tableName(tableName)
            .filterExpression("#attrName IN (" + inClause.toString() + ")")
            .expressionAttributeNames(expressionAttributeNames)
            .expressionAttributeValues(expressionAttributeValues)
            .build();

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

    /**
     * Generates a list of sample values for testing.
     *
     * <p>Helper method to generate a list of sample values for testing.
     *
     * @param valueType The type of values to generate (string, number, or boolean)
     * @param count The number of values to generate
     * @return List of generated attribute values
     */
    public static List<AttributeValue> generateSampleValues(String valueType, int count) {
        List<AttributeValue> values = new ArrayList<>();

        for (int i = 0; i < count; i++) {
            AttributeValue value;

            switch (valueType.toLowerCase(Locale.ROOT)) {
                case "string":
                    value = AttributeValue.builder().s("Value" + i).build();
                    break;
                case "number":
                    value = AttributeValue.builder().n(String.valueOf(i)).build();
                    break;
                case "boolean":
                    value = AttributeValue.builder().bool(i % 2 == 0).build();
                    break;
                default:
                    throw new IllegalArgumentException("Unsupported value type: " + valueType);
            }

            values.add(value);
        }

        return values;
    }
```
AWS SDK for Java 2.x を使用した複数の値の比較の使用例。  

```
    public static void exampleUsage(DynamoDbClient dynamoDbClient, String tableName) {
        System.out.println("Demonstrating how to compare multiple values with a single attribute in DynamoDB");

        try {
            // Example 1: Using the IN operator
            System.out.println("\nExample 1: Using the IN operator");
            List<AttributeValue> categories = List.of(
                AttributeValue.builder().s("Electronics").build(),
                AttributeValue.builder().s("Computers").build(),
                AttributeValue.builder().s("Accessories").build());

            QueryResponse inResponse = compareMultipleValues(
                dynamoDbClient,
                tableName,
                "Department",
                AttributeValue.builder().s("Retail").build(),
                "Category",
                categories);

            System.out.println("Found " + inResponse.count() + " items using IN operator");
            System.out.println("Items: " + inResponse.items());

            // Example 2: Using multiple OR conditions
            System.out.println("\nExample 2: Using multiple OR conditions");
            QueryResponse orResponse = compareWithOrConditions(
                dynamoDbClient,
                tableName,
                "Department",
                AttributeValue.builder().s("Retail").build(),
                "Category",
                categories);

            System.out.println("Found " + orResponse.count() + " items using OR conditions");
            System.out.println("Items: " + orResponse.items());

            // Example 3: Performance comparison
            System.out.println("\nExample 3: Performance comparison");
            Map<String, Object> perfComparison = comparePerformance(
                dynamoDbClient,
                tableName,
                "Department",
                AttributeValue.builder().s("Retail").build(),
                "Category",
                categories);

            if ((boolean) perfComparison.get("success")) {
                System.out.println("IN operator duration: " + perfComparison.get("inOperatorDuration") + " ns");
                System.out.println("OR conditions duration: " + perfComparison.get("orConditionsDuration") + " ns");
                System.out.println("IN operator found " + perfComparison.get("inOperatorItems") + " items");
                System.out.println("OR conditions found " + perfComparison.get("orConditionsItems") + " items");
                System.out.println("Expression complexity comparison:");
                System.out.println("  IN operator: " + perfComparison.get("inOperatorExpression"));
                System.out.println("  OR conditions: " + perfComparison.get("orConditionsExpression"));
            } else {
                System.out.println("Performance comparison failed: " + perfComparison.get("error"));
            }

            // Example 4: Using IN with a large number of values
            System.out.println("\nExample 4: Using IN with a large number of values");
            List<AttributeValue> productIds = generateSampleValues("string", 20);

            ScanResponse largeInResponse = scanWithLargeInClause(dynamoDbClient, tableName, "ProductId", productIds);

            System.out.println(
                "Found " + largeInResponse.count() + " items using IN with " + productIds.size() + " values");

            // Explain the benefits of using IN
            System.out.println("\nKey points about using the IN operator in DynamoDB:");
            System.out.println("1. The IN operator allows comparing a single attribute against multiple values");
            System.out.println("2. IN is more concise than using multiple OR conditions");
            System.out.println("3. IN counts as only 1 operator regardless of the number of values");
            System.out.println("4. Multiple OR conditions count as 1 operator per condition plus 1 per OR");
            System.out.println("5. Using IN helps stay within the 300 operator limit for complex expressions");
            System.out.println("6. IN can be used in filter expressions and condition expressions");
            System.out.println("7. The IN operator supports up to 100 comparison values");

        } catch (DynamoDbException e) {
            System.err.println("Error: " + e.getMessage());
            e.printStackTrace();
        }
    }
```
+ API の詳細については、「*AWS SDK for Java 2.x 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/goto/SdkForJavaV2/dynamodb-2012-08-10/Query)
  + [Scan](https://docs.aws.amazon.com/goto/SdkForJavaV2/dynamodb-2012-08-10/Scan)

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

**SDK for JavaScript (v3)**  
AWS SDK for JavaScript を使用して複数の値を単一の属性と比較する。  

```
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
    };
  }
}
```
AWS SDK for JavaScript を使用した複数の値の比較の使用例。  

```
/**
 * 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)

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

**SDK for Python (Boto3)**  
AWS SDK for Python (Boto3) を使用して複数の値を単一の属性と比較する。  

```
import boto3
from boto3.dynamodb.conditions import Attr, Key
from typing import Any, Dict, List, Optional


def compare_multiple_values(
    table_name: str,
    attribute_name: str,
    values_list: List[Any],
    partition_key_name: Optional[str] = None,
    partition_key_value: Optional[str] = None,
) -> Dict[str, Any]:
    """
    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.

    Args:
        table_name (str): The name of the DynamoDB table.
        attribute_name (str): The name of the attribute to compare against the values list.
        values_list (List[Any]): List of values to compare the attribute against.
        partition_key_name (Optional[str]): The name of the partition key attribute for query operations.
        partition_key_value (Optional[str]): The value of the partition key to query.

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

    # Create the filter expression using the is_in method
    filter_expression = Attr(attribute_name).is_in(values_list)

    # If partition key is provided, perform a query operation
    if partition_key_name and partition_key_value:
        key_condition = Key(partition_key_name).eq(partition_key_value)
        response = table.query(
            KeyConditionExpression=key_condition, FilterExpression=filter_expression
        )
    else:
        # Otherwise, perform a scan operation
        response = table.scan(FilterExpression=filter_expression)

    # Handle pagination if there are more results
    items = response.get("Items", [])
    while "LastEvaluatedKey" in response:
        if partition_key_name and partition_key_value:
            response = table.query(
                KeyConditionExpression=key_condition,
                FilterExpression=filter_expression,
                ExclusiveStartKey=response["LastEvaluatedKey"],
            )
        else:
            response = table.scan(
                FilterExpression=filter_expression, ExclusiveStartKey=response["LastEvaluatedKey"]
            )
        items.extend(response.get("Items", []))

    # Return the complete result
    return {"Items": items, "Count": len(items)}


def compare_with_or_conditions(
    table_name: str,
    attribute_name: str,
    values_list: List[Any],
    partition_key_name: Optional[str] = None,
    partition_key_value: Optional[str] = None,
) -> Dict[str, Any]:
    """
    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.

    Args:
        table_name (str): The name of the DynamoDB table.
        attribute_name (str): The name of the attribute to compare against the values list.
        values_list (List[Any]): List of values to compare the attribute against.
        partition_key_name (Optional[str]): The name of the partition key attribute for query operations.
        partition_key_value (Optional[str]): The value of the partition key to query.

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

    # Create a filter expression with multiple OR conditions
    filter_expression = None
    for value in values_list:
        condition = Attr(attribute_name).eq(value)
        if filter_expression is None:
            filter_expression = condition
        else:
            filter_expression = filter_expression | condition

    # If partition key is provided, perform a query operation
    if partition_key_name and partition_key_value and filter_expression:
        key_condition = Key(partition_key_name).eq(partition_key_value)
        response = table.query(
            KeyConditionExpression=key_condition, FilterExpression=filter_expression
        )
    elif filter_expression:
        # Otherwise, perform a scan operation
        response = table.scan(FilterExpression=filter_expression)
    else:
        # Return empty response if no values provided
        return {"Items": [], "Count": 0}

    # Handle pagination if there are more results
    items = response.get("Items", [])
    while "LastEvaluatedKey" in response:
        if partition_key_name and partition_key_value:
            response = table.query(
                KeyConditionExpression=key_condition,
                FilterExpression=filter_expression,
                ExclusiveStartKey=response["LastEvaluatedKey"],
            )
        else:
            response = table.scan(
                FilterExpression=filter_expression, ExclusiveStartKey=response["LastEvaluatedKey"]
            )
        items.extend(response.get("Items", []))

    # Return the complete result
    return {"Items": items, "Count": len(items)}
```
AWS SDK for Python (Boto3) を使用した複数の値の比較の使用例。  

```
def example_usage():
    """Example of how to use the compare_multiple_values function."""
    # Example parameters
    table_name = "Products"
    attribute_name = "Category"
    values_list = ["Electronics", "Computers", "Accessories"]

    print(f"Searching for products in any of these categories: {values_list}")

    # Using the IN operator (recommended approach)
    print("\nApproach 1: Using the IN operator")
    response = compare_multiple_values(
        table_name=table_name, attribute_name=attribute_name, values_list=values_list
    )

    print(f"Found {response['Count']} products in the specified categories")

    # Using multiple OR conditions (alternative approach)
    print("\nApproach 2: Using multiple OR conditions")
    response2 = compare_with_or_conditions(
        table_name=table_name, attribute_name=attribute_name, values_list=values_list
    )

    print(f"Found {response2['Count']} products in the specified categories")

    # Example with a query operation
    print("\nQuerying a specific manufacturer's products in multiple categories")
    partition_key_name = "Manufacturer"
    partition_key_value = "Acme"

    response3 = compare_multiple_values(
        table_name=table_name,
        attribute_name=attribute_name,
        values_list=values_list,
        partition_key_name=partition_key_name,
        partition_key_value=partition_key_value,
    )

    print(f"Found {response3['Count']} Acme products in the specified categories")

    # Explain the benefits of using the IN operator
    print("\nBenefits of using the IN operator:")
    print("1. More concise expression compared to multiple OR conditions")
    print("2. Better readability and maintainability")
    print("3. Potentially better performance with large value lists")
    print("4. Simpler code that's less prone to errors")
    print("5. Easier to modify when adding or removing values")
```
+ API の詳細については、『*AWS SDK for Python (Boto3) 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/goto/boto3/dynamodb-2012-08-10/Query)
  + [Scan](https://docs.aws.amazon.com/goto/boto3/dynamodb-2012-08-10/Scan)

------

AWS SDK デベロッパーガイドとコード例の詳細なリストについては、[AWS SDK で DynamoDB を使用する](sdk-general-information-section.md) を参照してください。このトピックには、使用開始方法に関する情報と、以前の SDK バージョンの詳細も含まれています。