The documentation for WAITFOR()没有明确规定所需的字符串格式。
这将等待2秒钟：
WAITFOR DELAY '00:00:02';
格式为hh:mi:ss.mmm。
As mentioned in other answers, all of the following will work for the standard string-based syntax.
WAITFOR DELAY '02:00' --Two hours
WAITFOR DELAY '00:02' --Two minutes
WAITFOR DELAY '00:00:02' --Two seconds
WAITFOR DELAY '00:00:00.200' --Two tenths of a seconds
There is also an alternative method of passing it a DATETIME value. You might think I'm confusing this with WAITFOR TIME, but it also works for WAITFOR DELAY.
Considerations for passing DATETIME:
It must be passed as a variable, so it isn't a nice one-liner anymore.
The delay is measured as the time since the Epoch ('1900-01-01').
For situations that require a variable amount of delay, it is much easier to manipulate a DATETIME than to properly format a VARCHAR.
How to wait for 2 seconds:
--Example 1
DECLARE @Delay1 DATETIME
SELECT @Delay1 = '1900-01-01 00:00:02.000'
WAITFOR DELAY @Delay1
--Example 2
DECLARE @Delay2 DATETIME
SELECT @Delay2 = dateadd(SECOND, 2, convert(DATETIME, 0))
WAITFOR DELAY @Delay2
A note on waiting for TIME vs DELAY:
Have you ever noticed that if you accidentally pass WAITFOR TIME a date that already passed, even by just a second, it will never return? Check it out:
--Example 3
DECLARE @Time1 DATETIME
SELECT @Time1 = getdate()
WAITFOR DELAY '00:00:01'
WAITFOR TIME @Time1 --WILL HANG FOREVER
Unfortunately, WAITFOR DELAY will do the same thing if you pass it a negative DATETIME value (yes, that's a thing).
--Example 4
DECLARE @Delay3 DATETIME
SELECT @Delay3 = dateadd(SECOND, -1, convert(DATETIME, 0))
WAITFOR DELAY @Delay3 --WILL HANG FOREVER
However, I would still recommend using WAITFOR DELAY over a static time because you can always confirm your delay is positive and it will stay that way for however long it takes your code to reach the WAITFOR statement.
这个怎么样？
WAITFOR DELAY '00:00:02';
如果您有“00:02”，它会将其解释为小时：分钟。