This should get you started:
declare @r datetime
--set @r = '2003-06-19 17:25:36.163'
--set @r = '2003-06-19 14:25:36.163'
set @r = '2003-06-19 07:25:36.163'
select
case
when (datepart(hh,@r) <= 16 and datepart(mm,@r) <= 30 and datepart(hh,@r) >= 7 and datepart(mm,@r) >= 30) then 'Day Shift'
else 'Evening Shift'
end
you can substitute the @r variable with your datetimefield, and include more criteria if you have more than one category.
Hope this helps,
Bygs