SET IMPLICIT_TRANSACTIONS (Transact-SQL)

適用于:SQL Server (Azure SQL Database Azure SQL 受控執行個體 Azure Synapse Analytics Analytics Platform System ( PDW) 的所有支援) 版本

將連線的 BEGIN TRANSACTION 模式設定為 implicit

主題連結圖示Transact-SQL 語法慣例

Syntax

SET IMPLICIT_TRANSACTIONS { ON | OFF }  

注意

若要檢視 SQL Server 2014 與更早版本的 Transact-SQL 語法,請參閱舊版文件

備註

當設定為 ON 時,系統是處於「隱含」 交易模式。 這表示,如果 @@TRANCOUNT = 0,下列任何 Transact-SQL 語句都會開始新的交易。 它相當於一個看不見的 BEGIN TRANSACTION 先被執行:

ALTER TABLE

FETCH

REVOKE

BEGIN TRANSACTION

GRANT

SELECT (請參閱底下的例外狀況)。

CREATE

Insert

TRUNCATE TABLE

刪除

MERGE

UPDATE

DROP

OPEN

 

當設定為 OFF,每個前面的 T-SQL 陳述式會受限於看不見的 BEGIN TRANSACTION 和看不見的 COMMIT TRANSACTION 陳述式。 當設定為 OFF 時,我們稱交易模式為「自動認可」。 如果您的 T-SQL 程式碼可見地發出 BEGIN TRANSACTION,我們稱交易模式為「明確」。

下列是幾個要了解的說明要點:

  • 當交易模式為隱含時,如果已經@@trancount > 0,就不會發出未看到的 BEGIN TRANSACTION。 不過,任何明確的 BEGIN TRANSACTION 語句仍會遞增@@TRANCOUNT。

  • 當 INSERT 語句和工作單位中的任何其他專案完成時,您必須發出 COMMIT TRANSACTION 語句,直到@@TRANCOUNT遞減為 0 為止。 或者您可以發出一個 ROLLBACK TRANSACTION。

  • 不會從資料表中選取的 SELECT 陳述式將無法開始隱含交易。 例如,SELECT GETDATE();SELECT 1, 'ABC'; 不需要交易。

  • 由於 ANSI 預設值的緣故,隱含交易可能會非預期地設定為 ON。 如需詳細資訊 ,請參閱 SET ANSI_DEFAULTS (Transact-SQL)

    IMPLICIT_TRANSACTIONS ON 並不常用。 在大部分 IMPLICIT_TRANSACTIONS 為 ON 的案例中,原因是已經做了 SET ANSI_DEFAULTS ON 的選擇。

  • SQL Server Native Client OLE DB Provider for SQL Server 和 SQL Server Native Client ODBC 驅動程式會在連接時自動將IMPLICIT_TRANSACTIONS設定為 OFF。 對於與 SQLClient 受控提供者的連線,以及透過 HTTP 端點來接收的 SOAP 要求,SET IMPLICIT_TRANSACTIONS 預設值為 OFF。

若要檢視 IMPLICIT_TRANSACTIONS 的目前設定,請執行下列查詢。

DECLARE @IMPLICIT_TRANSACTIONS VARCHAR(3) = 'OFF';  
IF ( (2 & @@OPTIONS) = 2 ) SET @IMPLICIT_TRANSACTIONS = 'ON';  
SELECT @IMPLICIT_TRANSACTIONS AS IMPLICIT_TRANSACTIONS;  

範例

下列 Transact-SQL 指令碼執行幾個不同的測試案例。 也提供文字輸出,其中顯示每個測試案例的詳細行為與結果。

-- Transact-SQL.  
-- Preparations.  
SET NOCOUNT ON;  
SET IMPLICIT_TRANSACTIONS OFF;  
GO  
WHILE (@@TranCount > 0) COMMIT TRANSACTION;  
GO  
IF (OBJECT_ID(N'dbo.t1',N'U') IS NOT NULL) DROP TABLE dbo.t1;  
GO  
CREATE table dbo.t1 (a INT);  
GO  
  
PRINT N'-------- [Test A] ---- OFF ----';  
PRINT N'[A.01] Now, SET IMPLICIT_TRANSACTIONS OFF.';  
PRINT N'[A.02] @@TranCount, at start, == ' + CAST(@@TRANCOUNT AS NVARCHAR(10));  
SET IMPLICIT_TRANSACTIONS OFF;  
GO 
INSERT INTO dbo.t1 VALUES (11);  
INSERT INTO dbo.t1 VALUES (12);  
PRINT N'[A.03] @@TranCount, after INSERTs, == ' + CAST(@@TRANCOUNT AS NVARCHAR(10));  
GO  
  
PRINT N' ';  
PRINT N'-------- [Test B] ---- ON ----';  
PRINT N'[B.01] Now, SET IMPLICIT_TRANSACTIONS ON.';  
PRINT N'[B.02] @@TranCount, at start, == ' + CAST(@@TRANCOUNT AS NVARCHAR(10));  
SET IMPLICIT_TRANSACTIONS ON;  
GO
INSERT INTO dbo.t1 VALUES (21);  
INSERT INTO dbo.t1 VALUES (22);  
PRINT N'[B.03] @@TranCount, after INSERTs, == ' + CAST(@@TRANCOUNT AS NVARCHAR(10));  
GO 
COMMIT TRANSACTION;  
PRINT N'[B.04] @@TranCount, after COMMIT, == ' + CAST(@@TRANCOUNT AS NVARCHAR(10));  
GO
  
PRINT N' ';  
PRINT N'-------- [Test C] ---- ON, then BEGIN TRAN ----';  
PRINT N'[C.01] Now, SET IMPLICIT_TRANSACTIONS ON.';  
PRINT N'[C.02] @@TranCount, at start, == ' + CAST(@@TRANCOUNT AS NVARCHAR(10));  
SET IMPLICIT_TRANSACTIONS ON;  
GO  
BEGIN TRANSACTION;  
INSERT INTO dbo.t1 VALUES (31);  
INSERT INTO dbo.t1 VALUES (32);  
PRINT N'[C.03] @@TranCount, after INSERTs, == ' + CAST(@@TRANCOUNT AS NVARCHAR(10));  
GO  
COMMIT TRANSACTION;  
PRINT N'[C.04] @@TranCount, after a COMMIT, == ' + CAST(@@TRANCOUNT AS NVARCHAR(10));  
COMMIT TRANSACTION;  
PRINT N'[C.05] @@TranCount, after another COMMIT, == ' + CAST(@@TRANCOUNT AS NVARCHAR(10));  
GO
  
PRINT N' ';  
PRINT N'-------- [Test D] ---- ON, INSERT, BEGIN TRAN, INSERT ----';  
PRINT N'[D.01] Now, SET IMPLICIT_TRANSACTIONS ON.';  
PRINT N'[D.02] @@TranCount, at start, == ' + CAST(@@TRANCOUNT AS NVARCHAR(10));  
SET IMPLICIT_TRANSACTIONS ON;  
GO 
INSERT INTO dbo.t1 VALUES (41);  
BEGIN TRANSACTION;  
INSERT INTO dbo.t1 VALUES (42);  
PRINT N'[D.03] @@TranCount, after INSERTs, == ' + CAST(@@TRANCOUNT AS NVARCHAR(10));  
GO 
COMMIT TRANSACTION;  
PRINT N'[D.04] @@TranCount, after a COMMIT, == ' + CAST(@@TRANCOUNT AS NVARCHAR(10));  
COMMIT TRANSACTION;  
PRINT N'[D.05] @@TranCount, after another COMMIT, == ' + CAST(@@TRANCOUNT AS NVARCHAR(10));  
GO
  
-- Clean up.  
SET IMPLICIT_TRANSACTIONS OFF;  
GO  
WHILE (@@TranCount > 0) COMMIT TRANSACTION;  
GO  
DROP TABLE dbo.t1;  
GO

接下來是前述 Transact-SQL 指令碼的文字輸出。

-- Text output from Transact-SQL:  
  
-------- [Test A] ---- OFF ----  
[A.01] Now, SET IMPLICIT_TRANSACTIONS OFF.  
[A.02] @@TranCount, at start, == 0  
[A.03] @@TranCount, after INSERTs, == 0  
  
-------- [Test B] ---- ON ----  
[B.01] Now, SET IMPLICIT_TRANSACTIONS ON.  
[B.02] @@TranCount, at start, == 0  
[B.03] @@TranCount, after INSERTs, == 1  
[B.04] @@TranCount, after COMMIT, == 0  
  
-------- [Test C] ---- ON, then BEGIN TRAN ----  
[C.01] Now, SET IMPLICIT_TRANSACTIONS ON.  
[C.02] @@TranCount, at start, == 0  
[C.03] @@TranCount, after INSERTs, == 2  
[C.04] @@TranCount, after a COMMIT, == 1  
[C.05] @@TranCount, after another COMMIT, == 0  
  
-------- [Test D] ---- ON, INSERT, BEGIN TRAN, INSERT ----  
[D.01] Now, SET IMPLICIT_TRANSACTIONS ON.  
[D.02] @@TranCount, at start, == 0  
[D.03] @@TranCount, after INSERTs, == 2  
[D.04] @@TranCount, after INSERTs, == 1  
[D.05] @@TranCount, after INSERTs, == 0  

以下為結果集。

另請參閱

ALTER TABLE (Transact-SQL)
BEGIN TRANSACTION (Transact-SQL)
CREATE TABLE (Transact-SQL)
DELETE (Transact-SQL)
DROP TABLE (Transact-SQL)
FETCH (Transact-SQL)
GRANT (Transact-SQL)
INSERT (Transact-SQL)
MERGE (Transact-SQL) OPEN (Transact-SQL)
REVOKE (Transact-SQL)
SELECT (Transact-SQL)
SET 陳述式 (Transact-SQL)
SET ANSI_DEFAULTS (Transact-SQL)
@@TRANCOUNT (Transact-SQL)
TRUNCATE TABLE (Transact-SQL)
UPDATE (Transact-SQL)