项目
04/01/2012

SAVE TRANSACTION (Transact-SQL)

在事务内设置保存点。

语法

SAVE { TRAN | TRANSACTION } { savepoint_name | @savepoint_variable }
[ ; ]

参数

savepoint_name
分配给保存点的名称。保存点名称必须符合标识符的规则，但长度不能超过 32 个字符。
@savepoint_variable
包含有效保存点名称的用户定义变量的名称。必须用 char、varchar、nchar 或 nvarchar 数据类型声明变量。如果长度超过 32 个字符，也可以传递到变量，但只使用前 32 个字符。

注释

用户可以在事务内设置保存点或标记。保存点可以定义在按条件取消某个事务的一部分后，该事务可以返回的一个位置。如果将事务回滚到保存点，则根据需要必须完成其他剩余的 Transact-SQL 语句和 COMMIT TRANSACTION 语句，或者必须通过将事务回滚到起始点完全取消事务。若要取消整个事务，请使用 ROLLBACK TRANSACTION transaction_name 语句。这将撤消事务的所有语句和过程。

在事务中允许有重复的保存点名称，但指定保存点名称的 ROLLBACK TRANSACTION 语句只将事务回滚到使用该名称的最近的 SAVE TRANSACTION。

在使用 BEGIN DISTRIBUTED TRANSACTION 显式启动或从本地事务升级的分布式事务中，不支持 SAVE TRANSACTION。

重要提示
当事务开始后，事务处理期间使用的资源将一直保留，直到事务完成（也就是锁定）。当将事务的一部分回滚到保存点时，将继续保留资源直到事务完成（或者回滚整个事务）。

权限

要求具有 public 角色的成员身份。

示例

下例说明，如果活动事务在存储过程执行之前启动，如何使用事务保存点只回滚由存储过程所做的修改。

USE AdventureWorks2008R2;
GO
IF EXISTS (SELECT name FROM sys.objects
           WHERE name = N'SaveTranExample')
    DROP PROCEDURE SaveTranExample;
GO
CREATE PROCEDURE SaveTranExample
    @InputCandidateID INT
AS
    -- Detect whether the procedure was called
    -- from an active transaction and save
    -- that for later use.
    -- In the procedure, @TranCounter = 0
    -- means there was no active transaction
    -- and the procedure started one.
    -- @TranCounter > 0 means an active
    -- transaction was started before the 
    -- procedure was called.
    DECLARE @TranCounter INT;
    SET @TranCounter = @@TRANCOUNT;
    IF @TranCounter > 0
        -- Procedure called when there is
        -- an active transaction.
        -- Create a savepoint to be able
        -- to roll back only the work done
        -- in the procedure if there is an
        -- error.
        SAVE TRANSACTION ProcedureSave;
    ELSE
        -- Procedure must start its own
        -- transaction.
        BEGIN TRANSACTION;
    -- Modify database.
    BEGIN TRY
        DELETE HumanResources.JobCandidate
            WHERE JobCandidateID = @InputCandidateID;
        -- Get here if no errors; must commit
        -- any transaction started in the
        -- procedure, but not commit a transaction
        -- started before the transaction was called.
        IF @TranCounter = 0
            -- @TranCounter = 0 means no transaction was
            -- started before the procedure was called.
            -- The procedure must commit the transaction
            -- it started.
            COMMIT TRANSACTION;
    END TRY
    BEGIN CATCH
        -- An error occurred; must determine
        -- which type of rollback will roll
        -- back only the work done in the
        -- procedure.
        IF @TranCounter = 0
            -- Transaction started in procedure.
            -- Roll back complete transaction.
            ROLLBACK TRANSACTION;
        ELSE
            -- Transaction started before procedure
            -- called, do not roll back modifications
            -- made before the procedure was called.
            IF XACT_STATE() <> -1
                -- If the transaction is still valid, just
                -- roll back to the savepoint set at the
                -- start of the stored procedure.
                ROLLBACK TRANSACTION ProcedureSave;
                -- If the transaction is uncommitable, a
                -- rollback to the savepoint is not allowed
                -- because the savepoint rollback writes to
                -- the log. Just return to the caller, which
                -- should roll back the outer transaction.

        -- After the appropriate rollback, echo error
        -- information to the caller.
        DECLARE @ErrorMessage NVARCHAR(4000);
        DECLARE @ErrorSeverity INT;
        DECLARE @ErrorState INT;

        SELECT @ErrorMessage = ERROR_MESSAGE();
        SELECT @ErrorSeverity = ERROR_SEVERITY();
        SELECT @ErrorState = ERROR_STATE();

        RAISERROR (@ErrorMessage, -- Message text.
                   @ErrorSeverity, -- Severity.
                   @ErrorState -- State.
                   );
    END CATCH
GO