嵌套事务

@@TRANCOUNT 函数记录当前事务的嵌套级别。每个 BEGIN TRANSACTION 语句使 @@TRANCOUNT 增加 1。每个 COMMIT TRANSACTION 或 COMMIT WORK 语句使 @@TRANCOUNT 减去 1。没有事务名称的 ROLLBACK WORK 或 ROLLBACK TRANSACTION 语句将回滚所有嵌套事务，并使 @@TRANCOUNT 减小到 0。使用一组嵌套事务中最外部事务的事务名称的 ROLLBACK TRANSACTION 将回滚所有嵌套事务，并使 @@TRANCOUNT 减小到 0。在无法确定是否已经在事务中时，可以用 SELECT @@TRANCOUNT 确定 @@TRANCOUNT 是等于 1 还是大于 1。如果 @@TRANCOUNT 等于 0，则表明不在事务中。

SET QUOTED_IDENTIFIER OFF;

GO

SET NOCOUNT OFF;

GO

CREATE TABLE TestTrans(Cola INT PRIMARY KEY,

               Colb CHAR(3) NOT NULL);

GO



CREATE PROCEDURE TransProc @PriKey INT, @CharCol CHAR(3) AS

BEGIN TRANSACTION InProc

INSERT INTO TestTrans VALUES (@PriKey, @CharCol)

INSERT INTO TestTrans VALUES (@PriKey + 1, @CharCol)

COMMIT TRANSACTION InProc;

GO

----------------------------------------------------------------------------

/* Start a transaction and execute TransProc. */

BEGIN TRANSACTION OutOfProc;

GO

EXEC TransProc 1, 'aaa';

GO

/* Roll back the outer transaction, this will

   roll back TransProc's nested transaction. */

ROLLBACK TRANSACTION OutOfProc;

GO

----------------------------------------------------------------------------

EXECUTE TransProc 3,'bbb';

GO

/* The following SELECT statement shows only rows 3 and 4 are 

   still in the table. This indicates that the commit

   of the inner transaction from the first EXECUTE statement of

   TransProc was overridden by the subsequent rollback. */

SELECT * FROM TestTrans;

from: http://wenku.baidu.com/view/7be79a0c844769eae009ed30.html

保存点：sqlserver  提供一种用于回滚事务的机制：Save Tran, 它不会对@@trancount产生任何

影响，只是标记回滚事务时可以到达的点。



DECLARE @nestFlag BIT

IF(@@TRANCOUNT>0)

BEGIN

	SET @nestedFlag = 1

	SAVE TRAN TestA

END

ELSE

BEGIN

	SET @nestFlag = 0

	BEGIN TRAN TestA

END

--执行业务操作，如果出错就回滚事务点，并立即返回

IF (@@error <> 0)

BEGIN

	ROLLBACK TRAN TestA

	RETURN 0

END

IF (@testedFlag=0)

BEGIN

	COMMIT TRAN TestA

END