Another example. . . Manipulating timestamps

declare @Today datetime
set @Today = convert(datetime,convert(char(10),getdate(),101))
declare @TodayHour datetime
set @TodayHour = dateadd(hh,(datepart(hh,getdate())),@Today)

Select @Today, @TodayHour

declare @Today15Min_pre datetime
set @Today15MIn_pre = dateadd(mi,16,@TodayHour)

declare @Today15Min datetime
set @Today15Min = dateadd(ms,-2,@Today15Min_pre)

Select @Today15min_pre, @Today15Min