How to add datetime field with a time field

Question

I have to add time value to existing datetime value using T-SQL in SQL Server 2012.

I was thinking that DATEADD function it might be a solution, but it is not...

Perhaps I have somehow time convert to datetime?

So I have

StartDate 2013-02-18 18:34:40.330 (datetime)

Interval 00:11:00.0000000 (time)

EndDate ? tsql ? (datetime)

Any clue?

Answer 1

DECLARE @d DATETIME = '2013-02-18T18:34:40.330',
        @t TIME(7)  = '00:11:00.0000000';

SELECT EndDate = DATEADD(SECOND, DATEDIFF(SECOND, 0, @t), @d);

Result:

EndDate
-----------------------
2013-02-18 18:45:40.330

Now, you really shouldn't be storing interval in a time column. time is meant to represent a point in time, not a duration. What happens when the interval is >= 24 hours? You should store the start time and end time of an event (those things are typically at least as relevant as the duration), and you can always calculate the duration from those points.