关于 日期 规整

ex:

1.按照30分钟规整 

1-1.

declare @dt datetime

set @dt = '2008-2-2 12:12:13'
select dateadd(minute,datediff(minute,0,@dt)/30*30,0)
-- 2008-02-02 12:00:00.000

set @dt = '2008-3-4 9:45:28 '
select dateadd(minute,datediff(minute,0,@dt)/30*30,0)

1-2. 先时间， 然后分钟进行规整

 select cast ( convert( varchar(14) ,  @dt , 121 ) +  case when  DATEPART (minute , @dt)  >= 30 then '30' else '00' end + ':00' as datetime )

   datepart Return:  Int