本文為英文版的機器翻譯版本，如內容有任何歧義或不一致之處，概以英文版為準。 # 使用 DynamoDB 專用 PartiQL 執行交易 本節說明如何搭配 DynamoDB 專用 PartiQL 使用交易。PartiQL 交易限制為全部 100 個陳述式 (動作)。 如需 DynamoDB 交易的詳細資訊，請參閱[管理包含 DynamoDB 交易的複雜工作流程](https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/transactions.html)。 **注意** 整個交易必須由讀取陳述式或寫入陳述式所組成。你不能在一個交易中混合兩者。EXISTS 函數為例外。可用類似於 [TransactWriteItems](https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/transaction-apis.html#transaction-apis-txwriteitems) API 操作中的 `ConditionCheck` 方式檢查項目特定屬性的條件。 **Topics** + [ ## 語法 ](#ql-reference.multiplestatements.transactions.syntax) + [ ## Parameters ](#ql-reference.multiplestatements.transactions.parameters) + [ ## 傳回值 ](#ql-reference.multiplestatements.transactions.return) + [ ## 範例 ](#ql-reference.multiplestatements.transactions.examples) ## 語法 ``` [ { "Statement":" statement ", "Parameters":[ { " parametertype " : " parametervalue " }, ...] } , ... ] ``` ## Parameters ***陳述式*** (必要) DynamoDB 專用 PartiQL 支援的陳述式。 整個交易必須由讀取陳述式或寫入陳述式所組成。你不能在一個交易中混合兩者。 ***parametertype*** (選用) DynamoDB 類型，如果在指定 PartiQL 陳述式時使用了參數。 ***parametervalue*** (選用) 參數值，如果在指定 PartiQL 陳述式時使用了參數。 ## 傳回值 此陳述式不會傳回寫入作業 (插入、更新或刪除) 的任何值。但是，它根據 WHERE 子句中指定的條件回傳讀取操作 (SELECT) 的不同值。 **注意** 如果任何單一 INSERT、UPDATE 或 DELETE 操作傳回錯誤，交易會取消並出現 `TransactionCanceledException` 例外狀況，且取消原因程式碼會包含個別單一操作的錯誤。 ## 範例 以下範例會以交易形式執行多個陳述式。 ------ #### [ AWS CLI ] 1. 將以下 JSON 程式碼儲存至名為 partiql.json 的檔案。 ``` [ { "Statement": "EXISTS(SELECT * FROM \"Music\" where Artist='No One You Know' and SongTitle='Call Me Today' and Awards is MISSING)" }, { "Statement": "INSERT INTO Music value {'Artist':?,'SongTitle':'?'}", "Parameters": [{\"S\": \"Acme Band\"}, {\"S\": \"Best Song\"}] }, { "Statement": "UPDATE \"Music\" SET AwardsWon=1 SET AwardDetail={'Grammys':[2020, 2018]} where Artist='Acme Band' and SongTitle='PartiQL Rocks'" } ] ``` 1. 在命令提示中執行下列命令。 ``` aws dynamodb execute-transaction --transact-statements file://partiql.json ``` ------ #### [ Java ] ``` public class DynamoDBPartiqlTransaction { public static void main(String[] args) { // Create the DynamoDB Client with the region you want AmazonDynamoDB dynamoDB = createDynamoDbClient("us-west-2"); try { // Create ExecuteTransactionRequest ExecuteTransactionRequest executeTransactionRequest = createExecuteTransactionRequest(); ExecuteTransactionResult executeTransactionResult = dynamoDB.executeTransaction(executeTransactionRequest); System.out.println("ExecuteTransaction successful."); // Handle executeTransactionResult } catch (Exception e) { handleExecuteTransactionErrors(e); } } private static AmazonDynamoDB createDynamoDbClient(String region) { return AmazonDynamoDBClientBuilder.standard().withRegion(region).build(); } private static ExecuteTransactionRequest createExecuteTransactionRequest() { ExecuteTransactionRequest request = new ExecuteTransactionRequest(); // Create statements List statements = getPartiQLTransactionStatements(); request.setTransactStatements(statements); return request; } private static List getPartiQLTransactionStatements() { List statements = new ArrayList(); statements.add(new ParameterizedStatement() .withStatement("EXISTS(SELECT * FROM "Music" where Artist='No One You Know' and SongTitle='Call Me Today' and Awards is MISSING)")); statements.add(new ParameterizedStatement() .withStatement("INSERT INTO "Music" value {'Artist':'?','SongTitle':'?'}") .withParameters(new AttributeValue("Acme Band"),new AttributeValue("Best Song"))); statements.add(new ParameterizedStatement() .withStatement("UPDATE "Music" SET AwardsWon=1 SET AwardDetail={'Grammys':[2020, 2018]} where Artist='Acme Band' and SongTitle='PartiQL Rocks'")); return statements; } // Handles errors during ExecuteTransaction execution. Use recommendations in error messages below to add error handling specific to // your application use-case. private static void handleExecuteTransactionErrors(Exception exception) { try { throw exception; } catch (TransactionCanceledException tce) { System.out.println("Transaction Cancelled, implies a client issue, fix before retrying. Error: " + tce.getErrorMessage()); } catch (TransactionInProgressException tipe) { System.out.println("The transaction with the given request token is already in progress, consider changing " + "retry strategy for this type of error. Error: " + tipe.getErrorMessage()); } catch (IdempotentParameterMismatchException ipme) { System.out.println("Request rejected because it was retried with a different payload but with a request token that was already used, " + "change request token for this payload to be accepted. Error: " + ipme.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()); } } } ``` ------ 下列範例顯示當 DynamoDB 讀取 WHERE 子句中指定之不同條件的項目時，不同的傳回值。 ------ #### [ AWS CLI ] 1. 將以下 JSON 程式碼儲存至名為 partiql.json 的檔案。 ``` [ // Item exists and projected attribute exists { "Statement": "SELECT * FROM "Music" WHERE Artist='No One You Know' and SongTitle='Call Me Today'" }, // Item exists but projected attributes do not exist { "Statement": "SELECT non_existent_projected_attribute FROM "Music" WHERE Artist='No One You Know' and SongTitle='Call Me Today'" }, // Item does not exist { "Statement": "SELECT * FROM "Music" WHERE Artist='No One I Know' and SongTitle='Call You Today'" } ] ``` 1. 在命令提示中執行命令。 ``` aws dynamodb execute-transaction --transact-statements file://partiql.json ``` 1. 會傳回下列回應： ``` { "Responses": [ // Item exists and projected attribute exists { "Item": { "Artist":{ "S": "No One You Know" }, "SongTitle":{ "S": "Call Me Today" } } }, // Item exists but projected attributes do not exist { "Item": {} }, // Item does not exist {} ] } ``` ------