Count elapsed business days between two dates

if exists (select * from dbo.sysobjects where id = object_id(N'[dbo].[ElapsedBusinessDays]') and xtype in (N'FN', N'IF', N'TF'))
drop function [dbo].[ElapsedBusinessDays]
GO

SET QUOTED_IDENTIFIER ON 
GO
SET ANSI_NULLS ON 
GO

CREATE FUNCTION [dbo].[ElapsedBusinessDays]
 (@Start smalldatetime, @End smalldatetime)
 RETURNS int
 AS
 BEGIN
 /* Description: Function designed to calculate the number of business days inclusively between two dates. */declare @Days int 
declare @DayIndex smallint
declare @HoldDate smalldatetime

--Make sure the end time is after the begin time
if @End < @Start
     begin
--Backwards. Swap them.
set @HoldDate = @Start
set @Start = @End
set @End = @HoldDate
     end

--Strip the time component off to ease comparisons to the holidays
set @Start = CONVERT(smalldatetime, CONVERT(varchar, @Start, 101 ) )
set @End = CONVERT(smalldatetime, CONVERT(varchar, @End, 101 ) )

set @Days = 0
set @HoldDate = @Start
while @HoldDate <= @End
     begin
--This will convert the current @Start day to a number between 1 and 7 with 1 = Monday and 7 = Sunday no matter what @@DATEFIRST is currently set to.
set @DayIndex = DATEPART( WeekDay, @HoldDate ) - ( 8 - @@DATEFIRST )
if @DayIndex < 1 set @DayIndex = @DayIndex + 7
if @DayIndex <= 5 set @Days = @Days + 1
set @HoldDate = DATEADD( Day, 1, @HoldDate )
     end

set @Days = @Days - ( SELECT COUNT(*)
FROM tblHolidays
WHERE HolidayDt >= @Start
AND HolidayDt <= @End
--This last condition is just to make sure someone didn't put in a holiday on a weekend which could cause negative days.
AND ( ( DATEPART( WeekDay, @HoldDate ) - ( 8 - @@DATEFIRST ) ) + case when (DATEPART( WeekDay, @HoldDate ) - ( 8 - @@DATEFIRST ) ) = 1 then 7 else 0 end ) <= 5 )

RETURN( @Days )
 END 

GO
SET QUOTED_IDENTIFIER OFF 
GO
SET ANSI_NULLS ON 
GO