SQL Server 2008中SQL之WaitFor

 SQL Server 2008中SQL应用系列--目录索引

在SQL Server 2005以上版本中,在一个增强的WaitFor命令,其作用可以和一个job相当。但使用更加简捷。

看MSDN:
http://msdn.microsoft.com/zh-cn/library/ms187331.aspx

语法为:

WAITFOR 
{
DELAY 'time_to_pass'
| TIME 'time_to_execute'
| [ ( receive_statement ) | ( get_conversation_group_statement ) ]
[ , TIMEOUT timeout ]
}

以下示例在晚上 10:20 (22:20) 执行存储过程 sp_update_job

USE msdb;
EXECUTE sp_add_job @job_name = 'TestJob';
BEGIN
WAITFOR TIME '22:20';
EXECUTE sp_update_job @job_name = 'TestJob',
@new_name = 'UpdatedJob';
END;
GO

以下示例在两小时的延迟后执行存储过程。注意:Delay最多不超过24小时


BEGIN
WAITFOR DELAY '02:00';
EXECUTE sp_helpdb;
END;
GO

以下示例显示如何对 WAITFOR DELAY 选项使用局部变量。将创建一个存储过程,该过程将等待可变的时间段,然后将经过的小时、分钟和秒数信息返回给用户。


USE AdventureWorks2008R2;
GO
IF OBJECT_ID('dbo.TimeDelay_hh_mm_ss','P') IS NOT NULL
DROP PROCEDURE dbo.TimeDelay_hh_mm_ss;
GO
CREATE PROCEDURE dbo.TimeDelay_hh_mm_ss
(
@DelayLength char(8)= '00:00:00'
)
AS
DECLARE @ReturnInfo varchar(255)
IF ISDATE('2000-01-01 ' + @DelayLength + '.000') = 0
BEGIN
SELECT @ReturnInfo = 'Invalid time ' + @DelayLength
+ ',hh:mm:ss, submitted.';
-- This PRINT statement is for testing, not use in production.
PRINT @ReturnInfo
RETURN(1)
END
BEGIN
WAITFOR DELAY @DelayLength
SELECT @ReturnInfo = 'A total time of ' + @DelayLength + ',
hh:mm:ss, has elapsed! Your time is up.
'
-- This PRINT statement is for testing, not use in production.
PRINT @ReturnInfo;
END;
GO
/* This statement executes the dbo.TimeDelay_hh_mm_ss procedure. */
EXEC TimeDelay_hh_mm_ss '00:00:10';
GO

执行结果:
A total time of 00:00:10, in hh:mm:ss, has elapsed.Your time is up.

小结:这是一种轻巧的解决方案。当你没有权限指定job时,可以考虑用WaitFor语句。

posted @ 2010-12-07 16:55  邀月  阅读(10596)  评论(5编辑  收藏  举报