Sql Server getting date difference in hours,min,sec

set ANSI_NULLS ON
set QUOTED_IDENTIFIER ON
GO
-- =============================================
-- Author: Renju.R
-- Create date: July 31
-- Description: getting date difference in hours,min,sec
-- =============================================
ALTER FUNCTION [dbo].[GetDateDiff]
(
@startDate datetime,
@finishDate datetime
)
RETURNS TABLE
AS
RETURN
(
SELECT DATEDIFF(hour,@startDate,@finishDate) as TotalHours,
DATEDIFF(minute,@startDate,@finishDate) - (DATEDIFF(hour,@startDate,@finishDate) * 60) as TotalMinutes,
DATEDIFF(second,@startDate,@finishDate) - (DATEDIFF(minute,@startDate,@finishDate) * 60) as TotalSeconds
)