Convert a given date to GMT

CREATE PROCEDURE iP_GMTConvrt

@DateIn VARCHAR(20),
@DateOut VARCHAR(50)OUTPUT

AS

--This Code Converts Local Time to GMT
Declare @DateUse VARCHAR(20)
Declare @TimeChg VARCHAR(20)
Declare @DayVal NUMERIC
Declare @GMT VARCHAR(20)

SET @DateUse = @DateIn --Get Current DateTime

If Month(@DateUse) >= 10 --Check To See if Date is Oct, Nov, or Dec
BEGIN
Set @TimeChg = '10/31/' + Cast(Year(@DateUse) as varchar) --Use Oct 31 as strt Point
END
ELSE
Set @TimeChg = '4/1/' + Cast(Year(@DateUse) as varchar) --Use April 1 as start point

Set @DayVal = DatePart(weekday,@TimeChg) --Is the Start Point a Sunday

If @DayVal <> 1 --If Not then when is the proper Time Change Sunday
If DatePart(m,@TimeChg) = 4 --Is the base the April Value
Begin
Set @TimeChg = DateAdd(d,8 - @DayVal,@TimeChg) --For April it is the first Sunday of the Month
End
Else
Set @TimeChg = DateAdd(d,-@DayVal + 1,@TimeChg) --For Oct it is the last Sunday of the Month

Set @TimeChg = DateAdd(hh,2,@TimeChg) --Alaways Happens at 2 am

If DatePart(m,@TimeChg) = 4 --If Time Change is Based on April
Begin
If @DateUse < @TimeChg --If DateUse < The Time Change Date & Time
Begin
Set @DateUse = DateAdd(hh,5,@DateUse) --GMT 5 hours ahead
End
Else
Set @DateUse = DateAdd(hh,4,@DateUse) --GMT 4 hours ahead
End
Else
If @DateUse < @TimeChg --If DateUse < The Time Change Date & Time
Begin
Set @DateUse = DateAdd(hh,4,@DateUse) --GMT 4 hours ahead
End
Else
Set @DateUse = DateAdd(hh,5,@DateUse) --GMT 5 hours ahead


--Set @GMT = DateDiff(s,'01/01/1970',@DateUse) --How many seconds since 1/1/1970 GMT to @DateUse GMT
Set @GMT = @DateUse -- Return in date format
--End GMT Code

Set @DateOut = @GMT