This function takes a given date and a date part and rounds up to the nearest date part.
In order to round '2010-11-03 17:44:10.117' up to the nearest hour ('2010-11-03 18:00:00.000')
select dbo.dateceiling(cast('2010-11-03 17:44:10.117' as datetime),'hh')
This function is helpful when aggregating lot dates by a date part (hour, day, etc).
See also: DateFloor Function