declare @dt datetime
set @dt= '2004/08/25 '
--一周內
select * from tb where datediff(day,@dt,getdate()) <=7 --@dt相當於日期字段
--一個月內
select * from tb where datediff(month,@dt,getdate()) <=1
--半年內
select * from tb where datediff(month,@dt,getdate()) <=6