Last week I was doing a comparison of 2 datetime fields, but I only wanted to do the comparison on the minute level. So I needed something to round the datetime to the nearest minute or down to the minute.
I found this great answer on SO:
DECLARE @dt DATETIME SET @dt = '09-22-2007 15:07:38.850' SELECT DATEADD(mi, DATEDIFF(mi, 0, @dt), 0)
SELECT DATEADD(mi, DATEDIFF(mi, 0, DATEADD(s, 30, @dt)), 0)