CREATE FUNCTION dbo.DiffBetweenDates(
@StartDT DATETIME,
@EndDT DATETIME)
RETURNS VARCHAR(30)
AS
BEGIN

DECLARE @intMin Int,
@intHrs Int,
@intDys Int,
@TotalMin Int,
@strOUTPUT Varchar(30)

SET @TotalMin = ABS(DATEDIFF(mi, @StartDT, @EndDT))
SET @intDys = @TotalMin / (24*60)
SET @intHrs = (@TotalMin-(@intDys*24*60)) / 60
SET @intMin = @TotalMin-((@intDys*24*60)+(@intHrs*60))

If @StartDT <= @EndDT
Begin
SET @strOUTPUT = CAST(@intDys as varchar(5)) + 'Days, ' + CAST(@intHrs as varchar(2)) + 'Hours, ' + cast( @intMin as varchar(2)) + 'Minutes'
End
Else
Begin
SET @strOUTPUT = '-(' + cast( @intDys as varchar(5)) + 'Days, ' + cast( @intHrs as varchar(2)) + 'Hours, ' + cast( @intMin as varchar(2)) + 'Minutes' + ')'
End

RETURN @strOUTPUT

END