如何在SQL Server中比较日期时间？

Question

I have to show the date 2018/01/30 if the datetime is between 2018/01/30 04:59:59.000 and 2018/01/31 04:59:59.000

I have a table called DataEntry . I want to move those records by date as per my criteria.

This DataEntry table have TransferTime that datatype is datetime.

As per my criteria if the TransferTime is 2018/01/30 01:30:59.000 then the date should be 2018/01/29

Answer 1

I think you can simply just write like this:

select 
 case when DATEPART(HOUR,'2018/01/30 01:30:59.000') >= 05 then cast('2018/01/30 01:30:59.000' as date) 
      else cast(dateadd(Dd,-1,'2018/01/30 01:30:59.000' )as date) 
 end 

Answer 2

This is somewhat of a guess on vague logic, but perhaps using CONVERT and DATEADD ?

WITH VTE AS(
    SELECT CONVERT(datetime2(3),DT) AS DT
    FROM (VALUES('20180130 04:59:59.000'),('20180131 01:00:34.000'),('20180130 01:30:59.000')) V(DT))
SELECT CONVERT(date, DATEADD(SECOND, -17999,DT)) AS D, DT
FROM VTE;

It's worth noting that you, oddly, state that '20180130 04:59:59.000' AND ''20180131 04:59:59.000' should both be on the same day, ( '20180130' ). This doesn't make any sense, as Days don't overlap like that. Thus the latter time would show '20180131' , as it's exactly 24 hours later.

If the former time should actually be '20180129' , then change -17999 to -18000 , or SECOND,-17999 to HOUR, -5 .

Answer 3

this will do too:

select cast(dateadd(second, -17999,Transfertime) as date)

being 17999 = 4hs59m59s in seconds