在 SQL 中启动和监控代理作业的简单 SQL 查询

Question

（从链接Executing SQL Server Agent Job from a stored procedure and returning job result获取的查询）

下面代码中@time_constraint的值是什么

WHILE @time_constraint = @ok        
    @time_constraint ?
    @ok?** Here @time_Constrain denotes???????

---

use msdb
-- Start job
DECLARE @job_name NVARCHAR(MAX) = 'Demo_Test'
EXEC msdb.dbo.sp_start_job @job_name = @job_name


-- Wait for job to finish
DECLARE @job_history_id AS INT = NULL

WHILE @time_constraint = @ok
BEGIN
    SELECT TOP 1 @job_history_id = activity.job_history_id
    FROM msdb.dbo.sysjobs jobs
    INNER JOIN msdb.dbo.sysjobactivity activity ON activity.job_id = jobs.job_id
    WHERE jobs.name = @job_name
    ORDER BY activity.start_execution_date DESC

    IF @job_history_id IS NULL
    BEGIN
        WAITFOR DELAY '00:00:10'
        CONTINUE
    END
    ELSE
        BREAK
END


-- Check exit code
SELECT history.run_status
FROM msdb.dbo.sysjobhistory history
WHERE history.instance_id = @job_history_id

Answer 1

循环检查作业历史记录的位置。如果有，则中断循环，如果没有，则继续使用WAITFOR 等待。由于永远等待可能是一个坏主意，因此应该有一个额外的时间限制条件。这就是作者对@time_constraint = @ok 的意思，虽然名字不是最好的。

例如：

DECLARE @MaxWaitingTimeInMinutes INT = 5

DECLARE @StartTime DATETIME = GETDATE()

WHILE DATEDIFF(MINUTE, @StartTime, GETDATE()) <= @MaxWaitingTimeInMinutes
BEGIN

    -- Check for job's history. Break if exists, wait if not.

END

另一个例子：

DECLARE @WaitUntil DATETIME = DATEADD(MINUTE, 5, GETDATE())

WHILE GETDATE() <= @WaitUntil
BEGIN

    -- Check for job's history. Break if exists, wait if not.

END

Answer 2

全文参考如下，线索在评论中

“您可能需要检查允许 WHILE 循环运行多长时间。我选择将该部分排除在示例之外。”

如 cmets 中所述，您应该插入一个检查以阻止代码永远运行，例如：

DECLARE @time_constraint datetime 
DECLARE @ok datetime

SET @time_constraint = DATEADD(second, 5, GETDATE()) -- Run for 5 seconds 
SET @ok = GETDATE()

SELECT @time_constraint as future, @ok as [current]

WHILE @time_constraint > @ok BEGIN      
   SELECT @ok = GETDATE() 
END

对于所有不允许使用 OPENROWSET 命令的人， 这可能会有所帮助。我在这里找到了解决方案的起点：

http://social.msdn.microsoft.com/Forums/en-US/89659729-fea8-4df0-8057-79e0a437b658/dynamically-checking-job-status-with-tsql

这取决于以下事实： 作业后首先填充 msdb.dbo.sysjobactivity 表 以一种或另一种方式结束。

-- Start job
DECLARE @job_name NVARCHAR(MAX) = 'JobName'
EXEC msdb.dbo.sp_start_job @job_name = @job_name


-- Wait for job to finish
DECLARE @job_history_id AS INT = NULL

WHILE @time_constraint = @ok
BEGIN
    SELECT TOP 1 @job_history_id = activity.job_history_id
    FROM msdb.dbo.sysjobs jobs
    INNER JOIN msdb.dbo.sysjobactivity activity ON activity.job_id = jobs.job_id
    WHERE jobs.name = @job_name
    ORDER BY activity.start_execution_date DESC

    IF @job_history_id IS NULL
    BEGIN
        WAITFOR DELAY '00:00:10'
        CONTINUE
    END
    ELSE
        BREAK
END


-- Check exit code
SELECT history.run_status
FROM msdb.dbo.sysjobhistory history
WHERE history.instance_id = @job_history_id

您可能需要检查 WHILE 循环的持续时间 允许运行。我选择将该部分排除在示例之外。

Microsoft 退出代码等指南： http://technet.microsoft.com/en-us/library/ms174997.aspx