select datediff(hour,'2014-11-25 22:59:0.000','2014-11-25 23:00:00.000') output 1 which is wrong .i have written a new function that calculates the correct time diff.plz see if it is correct

Create function [dbo].[fn_TimeDiff](@ClassicDate datetime,@NowDate datetime)
RETURNS @Table Table (HoursDiff float,MinuteDiff float,SecondDiff float,MilliSecondDiff float)
AS
Begin
DECLARE @NowMilliSeconds float
Declare @ClassicMilliSeconds float
DECLARE @HourDiff float
DECLARE @MinuteDiff float
DECLARE @SecondDiff float
DECLARE @MilliSecondDiff float
DECLARE @GrandDiffInMilliSeconds float
set @NowMilliSeconds =0
set @ClassicMilliSeconds =0
set @HourDiff =0
set @MinuteDiff =0
set @SecondDiff =0
set @MilliSecondDiff =0
set @GrandDiffInMilliSeconds =0


SET @NowMilliSeconds=(DATEPART(Hour,@NowDate)*3600000)+
                    (DATEPART(MINUTE,@NowDate)*60000)+
                    (DATEPART(SECOND,@NowDate)*1000)+
                     DATEPART(MILLISECOND,@NowDate)
                     
 SET @ClassicMilliSeconds=(DATEPART(Hour,@ClassicDate)*3600000)+
                    (DATEPART(MINUTE,@ClassicDate)*60000)+
                    (DATEPART(SECOND,@ClassicDate)*1000)+
                     DATEPART(MILLISECOND,@ClassicDate)
                     
 IF((@NowMilliSeconds-@ClassicMilliSeconds)>0)
 BEGIN                    
	 SET @GrandDiffInMilliSeconds=@NowMilliSeconds-@ClassicMilliSeconds--in milliseconds
	 SET @GrandDiffInMilliSeconds=@GrandDiffInMilliSeconds/3600000--in hours
	 SET @HourDiff=floor(@GrandDiffInMilliSeconds)--numeric part in hours
	 IF((@GrandDiffInMilliSeconds-@HourDiff)>0)
	 BEGIN
		 set @MinuteDiff=@GrandDiffInMilliSeconds-@HourDiff--decimal part in hours
		 IF(@MinuteDiff>0)
		 Begin
			SET @MinuteDiff=@MinuteDiff*60---in minutes
			IF((@MinuteDiff-floor(@MinuteDiff))>0)
			BEGIN
				SET @SecondDiff=@MinuteDiff-floor(@MinuteDiff)--decimal part
			END	
				Set @MinuteDiff=floor(@MinuteDiff) -- get minutes
				IF(@SecondDiff>0)
				BEGIN
					SET @SecondDiff=@SecondDiff*60 --get seconds
					IF((@SecondDiff-Floor(@SecondDiff))>0)
					BEGIN
					SET @MilliSecondDiff=@SecondDiff-Floor(@SecondDiff)--
					END
					SET @SecondDiff=floor(@SecondDiff)
				
			    END
		 END
	 END
  END
	 
	 
insert into @Table(HoursDiff ,MinuteDiff,SecondDiff ,MilliSecondDiff)
 values
 (@HourDiff,@MinuteDiff,@SecondDiff,@MilliSecondDiff)
 return

END