# PartiQL for DynamoDB 入门 本节介绍如何从 Amazon DynamoDB 控制台、AWS Command Line Interface (AWS CLI) 和 DynamoDB API 使用 PartiQL for DynamoDB。 在以下 DynamoDB 例中，[DynamoDB 入门](https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/GettingStartedDynamoDB.html)教程中定义的 DynamoDB 表是一个前提条件。 有关使用 DynamoDB 控制台、AWS Command Line Interface 或 DynamoDB API 访问 DynamoDB 的信息，请参阅[访问 DynamoDB](https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/AccessingDynamoDB.html)。 要[下载](https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/workbench.settingup.html)并使用 [NoSQL Workbench](https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/workbench.html) 生成 [PartiQL for DynamoDB](https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/ql-reference.html) 语句，请选择 NoSQL Workbench for DynamoDB [操作生成器](https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/workbench.querybuilder.operationbuilder.html)右上角的 **PartiQL operations**（PartiQL 操作）。 ------ #### [ Console ] ![\[PartiQL 编辑器界面，显示对 Music 表运行查询操作的结果。\]](http://docs.aws.amazon.com/zh_cn/amazondynamodb/latest/developerguide/images/partiqlgettingstarted.png) 1. 登录 AWS 管理控制台，打开 DynamoDB 控制台：[https://console.aws.amazon.com/dynamodb/](https://console.aws.amazon.com/dynamodb/)。 1. 在控制台左侧的导航窗格中，选择 **PartiQL editor (PartiQL 编辑器)**。 1. 选择 **Music** 表。 1. 选择 **Query table (查询表)**。此操作生成不会导致完整表扫描的查询。 1. 将 `partitionKeyValue` 替换为字符串值 `Acme Band`。将 `sortKeyValue` 替换为字符串值 `Happy Day`。 1. 选择 **Run (运行)** 按钮。 1. 选择 **Table view (表视图)** 或 **JSON view (JSON 视图)** 按钮，查看查询结果。 ------ #### [ NoSQL workbench ] ![\[NoSQL Workbench 界面。它显示一条 PartiQL SELECT 语句，您可以对 Music 表运行该语句。\]](http://docs.aws.amazon.com/zh_cn/amazondynamodb/latest/developerguide/images/workbench/partiql.single.png) 1. 选择 **PartiQL statement (PartiQL 语句)**。 1. 输入以下 PartiQL [SELECT 语句](https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/ql-reference.select.html) ``` SELECT * FROM Music WHERE Artist=? and SongTitle=? ``` 1. 指定 `Artist` 和 `SongTitle` 参数值： 1. 选择 **Optional request parameters (可选请求参数)**。 1. 选择 **Add new parameters (添加新参数)**。 1. 选择属性类型 **string** 和值 `Acme Band`。 1. 重复步骤 b 和 c，然后选择类型 **string** 和值 `PartiQL Rocks`。 1. 如果要生成代码，请选择 **Generate code (生成代码)**。 从显示的选项卡中选择所需的语言。现在，您便可复制此代码并在应用程序中使用它。 1. 如果要立即执行操作，请选择 **Run (执行)**。 ------ #### [ AWS CLI ] 1. 使用 INSERT PartiQL 语句在 `Music` 表中创建项目。 ``` aws dynamodb execute-statement --statement "INSERT INTO Music \ VALUE \ {'Artist':'Acme Band','SongTitle':'PartiQL Rocks'}" ``` 1. 使用 SELECT PartiQL 语句从 Music 表中检索项目。 ``` aws dynamodb execute-statement --statement "SELECT * FROM Music \ WHERE Artist='Acme Band' AND SongTitle='PartiQL Rocks'" ``` 1. 使用 INSERT PartiQL 语句在 `Music` 表中更新项目。 ``` aws dynamodb execute-statement --statement "UPDATE Music \ SET AwardsWon=1 \ SET AwardDetail={'Grammys':[2020, 2018]} \ WHERE Artist='Acme Band' AND SongTitle='PartiQL Rocks'" ``` 为 `Music` 表中的项目添加列表值。 ``` aws dynamodb execute-statement --statement "UPDATE Music \ SET AwardDetail.Grammys =list_append(AwardDetail.Grammys,[2016]) \ WHERE Artist='Acme Band' AND SongTitle='PartiQL Rocks'" ``` 为 `Music` 表中的项目移除列表值。 ``` aws dynamodb execute-statement --statement "UPDATE Music \ REMOVE AwardDetail.Grammys[2] \ WHERE Artist='Acme Band' AND SongTitle='PartiQL Rocks'" ``` 为 `Music` 表中的项目添加映射成员。 ``` aws dynamodb execute-statement --statement "UPDATE Music \ SET AwardDetail.BillBoard=[2020] \ WHERE Artist='Acme Band' AND SongTitle='PartiQL Rocks'" ``` 为 `Music` 表中的项目添加新字符串集属性。 ``` aws dynamodb execute-statement --statement "UPDATE Music \ SET BandMembers =<<'member1', 'member2'>> \ WHERE Artist='Acme Band' AND SongTitle='PartiQL Rocks'" ``` 为 `Music` 表中的项目更新字符串集属性。 ``` aws dynamodb execute-statement --statement "UPDATE Music \ SET BandMembers =set_add(BandMembers, <<'newmember'>>) \ WHERE Artist='Acme Band' AND SongTitle='PartiQL Rocks'" ``` 1. 使用 DELETE PartiQL 语句从 `Music` 表删除项目。 ``` aws dynamodb execute-statement --statement "DELETE FROM Music \ WHERE Artist='Acme Band' AND SongTitle='PartiQL Rocks'" ``` ------ #### [ Java ] ``` import java.util.ArrayList; import java.util.List; import com.amazonaws.AmazonClientException; import com.amazonaws.AmazonServiceException; import software.amazon.dynamodb.AmazonDynamoDB; import software.amazon.dynamodb.AmazonDynamoDBClientBuilder; import software.amazon.dynamodb.model.AttributeValue; import software.amazon.dynamodb.model.ConditionalCheckFailedException; import software.amazon.dynamodb.model.ExecuteStatementRequest; import software.amazon.dynamodb.model.ExecuteStatementResult; import software.amazon.dynamodb.model.InternalServerErrorException; import software.amazon.dynamodb.model.ItemCollectionSizeLimitExceededException; import software.amazon.dynamodb.model.ProvisionedThroughputExceededException; import software.amazon.dynamodb.model.RequestLimitExceededException; import software.amazon.dynamodb.model.ResourceNotFoundException; import software.amazon.dynamodb.model.TransactionConflictException; public class DynamoDBPartiQGettingStarted { public static void main(String[] args) { // Create the DynamoDB Client with the region you want AmazonDynamoDB dynamoDB = createDynamoDbClient("us-west-1"); try { // Create ExecuteStatementRequest ExecuteStatementRequest executeStatementRequest = new ExecuteStatementRequest(); List parameters= getPartiQLParameters(); //Create an item in the Music table using the INSERT PartiQL statement processResults(executeStatementRequest(dynamoDB, "INSERT INTO Music value {'Artist':?,'SongTitle':?}", parameters)); //Retrieve an item from the Music table using the SELECT PartiQL statement. processResults(executeStatementRequest(dynamoDB, "SELECT * FROM Music where Artist=? and SongTitle=?", parameters)); //Update an item in the Music table using the UPDATE PartiQL statement. processResults(executeStatementRequest(dynamoDB, "UPDATE Music SET AwardsWon=1 SET AwardDetail={'Grammys':[2020, 2018]} where Artist=? and SongTitle=?", parameters)); //Add a list value for an item in the Music table. processResults(executeStatementRequest(dynamoDB, "UPDATE Music SET AwardDetail.Grammys =list_append(AwardDetail.Grammys,[2016]) where Artist=? and SongTitle=?", parameters)); //Remove a list value for an item in the Music table. processResults(executeStatementRequest(dynamoDB, "UPDATE Music REMOVE AwardDetail.Grammys[2] where Artist=? and SongTitle=?", parameters)); //Add a new map member for an item in the Music table. processResults(executeStatementRequest(dynamoDB, "UPDATE Music set AwardDetail.BillBoard=[2020] where Artist=? and SongTitle=?", parameters)); //Add a new string set attribute for an item in the Music table. processResults(executeStatementRequest(dynamoDB, "UPDATE Music SET BandMembers =<<'member1', 'member2'>> where Artist=? and SongTitle=?", parameters)); //update a string set attribute for an item in the Music table. processResults(executeStatementRequest(dynamoDB, "UPDATE Music SET BandMembers =set_add(BandMembers, <<'newmember'>>) where Artist=? and SongTitle=?", parameters)); //Retrieve an item from the Music table using the SELECT PartiQL statement. processResults(executeStatementRequest(dynamoDB, "SELECT * FROM Music where Artist=? and SongTitle=?", parameters)); //delete an item from the Music Table processResults(executeStatementRequest(dynamoDB, "DELETE FROM Music where Artist=? and SongTitle=?", parameters)); } catch (Exception e) { handleExecuteStatementErrors(e); } } private static AmazonDynamoDB createDynamoDbClient(String region) { return AmazonDynamoDBClientBuilder.standard().withRegion(region).build(); } private static List getPartiQLParameters() { List parameters = new ArrayList(); parameters.add(new AttributeValue("Acme Band")); parameters.add(new AttributeValue("PartiQL Rocks")); return parameters; } private static ExecuteStatementResult executeStatementRequest(AmazonDynamoDB client, String statement, List parameters ) { ExecuteStatementRequest request = new ExecuteStatementRequest(); request.setStatement(statement); request.setParameters(parameters); return client.executeStatement(request); } private static void processResults(ExecuteStatementResult executeStatementResult) { System.out.println("ExecuteStatement successful: "+ executeStatementResult.toString()); } // Handles errors during ExecuteStatement execution. Use recommendations in error messages below to add error handling specific to // your application use-case. private static void handleExecuteStatementErrors(Exception exception) { try { throw exception; } catch (ConditionalCheckFailedException ccfe) { System.out.println("Condition check specified in the operation failed, review and update the condition " + "check before retrying. Error: " + ccfe.getErrorMessage()); } catch (TransactionConflictException tce) { System.out.println("Operation was rejected because there is an ongoing transaction for the item, generally " + "safe to retry with exponential back-off. Error: " + tce.getErrorMessage()); } catch (ItemCollectionSizeLimitExceededException icslee) { System.out.println("An item collection is too large, you\'re using Local Secondary Index and exceeded " + "size limit of items per partition key. Consider using Global Secondary Index instead. Error: " + icslee.getErrorMessage()); } catch (Exception e) { handleCommonErrors(e); } } private static void handleCommonErrors(Exception exception) { try { throw exception; } catch (InternalServerErrorException isee) { System.out.println("Internal Server Error, generally safe to retry with exponential back-off. Error: " + isee.getErrorMessage()); } catch (RequestLimitExceededException rlee) { System.out.println("Throughput exceeds the current throughput limit for your account, increase account level throughput before " + "retrying. Error: " + rlee.getErrorMessage()); } catch (ProvisionedThroughputExceededException ptee) { System.out.println("Request rate is too high. If you're using a custom retry strategy make sure to retry with exponential back-off. " + "Otherwise consider reducing frequency of requests or increasing provisioned capacity for your table or secondary index. Error: " + ptee.getErrorMessage()); } catch (ResourceNotFoundException rnfe) { System.out.println("One of the tables was not found, verify table exists before retrying. Error: " + rnfe.getErrorMessage()); } catch (AmazonServiceException ase) { System.out.println("An AmazonServiceException occurred, indicates that the request was correctly transmitted to the DynamoDB " + "service, but for some reason, the service was not able to process it, and returned an error response instead. Investigate and " + "configure retry strategy. Error type: " + ase.getErrorType() + ". Error message: " + ase.getErrorMessage()); } catch (AmazonClientException ace) { System.out.println("An AmazonClientException occurred, indicates that the client was unable to get a response from DynamoDB " + "service, or the client was unable to parse the response from the service. Investigate and configure retry strategy. "+ "Error: " + ace.getMessage()); } catch (Exception e) { System.out.println("An exception occurred, investigate and configure retry strategy. Error: " + e.getMessage()); } } } ``` ------ ## 使用参数化语句 您可以使用问号（`?`）占位符并在 `Parameters` 字段中单独提供值，而不是将值直接嵌入到 PartiQL 语句字符串中。每个 `?` 值都按提供的顺序替换为相应的参数值。 使用参数化语句是一种最佳实践，因为这可以将语句结构与数据值分开，从而使语句更易于读懂和重复使用。这还可以避免在语句字符串中手动格式化和转义属性值的需求。 `ExecuteStatement`、`BatchExecuteStatement` 和 `ExecuteTransaction` 操作支持参数化语句。 以下示例使用分区键和排序键的参数化值从 `Music` 表中检索项目。 ------ #### [ AWS CLI parameterized ] ``` aws dynamodb execute-statement \ --statement "SELECT * FROM \"Music\" WHERE Artist=? AND SongTitle=?" \ --parameters '[{"S": "Acme Band"}, {"S": "PartiQL Rocks"}]' ``` ------ #### [ Java parameterized ] ``` List parameters = new ArrayList<>(); parameters.add(new AttributeValue("Acme Band")); parameters.add(new AttributeValue("PartiQL Rocks")); ExecuteStatementRequest request = new ExecuteStatementRequest() .withStatement("SELECT * FROM Music WHERE Artist=? AND SongTitle=?") .withParameters(parameters); ExecuteStatementResult result = dynamoDB.executeStatement(request); ``` ------ #### [ Python parameterized ] ``` response = dynamodb_client.execute_statement( Statement="SELECT * FROM Music WHERE Artist=? AND SongTitle=?", Parameters=[ {'S': 'Acme Band'}, {'S': 'PartiQL Rocks'} ] ) ``` ------ **注意** 前面入门部分中的 Java 示例自始至终都在使用参数化语句。`getPartiQLParameters()` 方法构建参数列表，每条语句都使用 `?` 占位符而不是内联值。