从varchar中选择日期差异

Question

我需要找到DateDiff nvarchar对getdate值的方法：

create table dbo.DateChk
([DateString] [nvarchar](24) NULL)
insert into dbo.DateChk (DateString) values ('20130112'),('20131121'), ('20130924'),('20130515')

select getdate(), DateString 
---,  getdate()- DateString as DateDiff
from dbo.DateChk

Answer 1

只需使用DATEDIFF功能：

select getdate(), DateString 
---,  getdate()- DateString as DateDiff
, DATEDIFF(DAY,  DateString, getdate())
from dbo.DateChk

http://www.w3schools.com/sql/func_datediff_mysql.asp

http://msdn.microsoft.com/en-us/library/ms189794.aspx