B. 使用 WAITFOR DELAY
下例说明如何对 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量,然后将所经过的小时、分钟和秒数信息返回给用户。
CREATE PROCEDURE time_delay @@DELAYLENGTH char(9)
AS
DECLARE @@RETURNINFO varchar(255)
BEGIN
WAITFOR DELAY @@DELAYLENGTH
SELECT @@RETURNINFO = 'A total time of ' +
SUBSTRING(@@DELAYLENGTH, 1, 3) +
' hours, ' +
SUBSTRING(@@DELAYLENGTH, 5, 2) +
' minutes, and ' +
SUBSTRING(@@DELAYLENGTH, 8, 2) +
' seconds, ' +
'has elapsed! Your time is up.'
PRINT @@RETURNINFO
END
GO
-- This next statement executes the time_delay procedure.
EXEC time_delay '000:00:10'
GO