一种在t-SQL中选择两个日期之间的日期的方法

Question

Say, I have two DATETIME2 columns and I need to select dates between the two. Example: 1/1/2012 08:00 and 1/1/2012 09:00 should produce 1/1/2012 08:30.

I'm trying this:

SELECT CAST((CAST(dtOut AS float(53)) + 
       CAST(dtIn AS float(53))) / 2 AS DATETIME2) FROM t;

But I get an error that explicit conversion from DATETIME2 is not allowed.

Any idea how to do it?

Answer 1

DateDiff will find the difference between two dates.

 select Dateadd(n, DATEDIFF(n, dtIn, dtOut)/2, dtIn) FROM t

As an aside, your method would work if the fields were datetime, not datetime2.

Answer 2

试试这个。

  select Dateadd(n, DATEDIFF(n, '1/1/2012 08:00', '1/1/2012 09:00')/2, '1/1/2012 08:00');

Answer 3

declare @d1 datetime2, @d2 datetime2
select @d1='1/1/2012 08:00',@d2='1/1/2012 09:00'
 select dateadd(minute,datediff(minute ,@d1,@d2)/2.0,@d1)

Answer 4

选择dateadd（SECOND，datediff（SECOND，dtIn，dtOut）/2.0,dtIn）