Count work days between two dates

Question

How can I calculate the number of work days between two dates in SQL Server?

Monday to Friday and it must be T-SQL.

Answer 1

I found the below TSQL a fairly elegant solution (I don't have permissions to run functions). I found the DATEDIFF ignores DATEFIRST and I wanted my first day of the week to be a Monday. I also wanted the first working day to be set a zero and if it falls on a weekend Monday will be a zero. This may help someone who has a slightly different requirement :)

It does not handle bank holidays

SET DATEFIRST 1
SELECT
,(DATEDIFF(DD,  [StartDate], [EndDate]))        
-(DATEDIFF(wk,  [StartDate], [EndDate]))        
-(DATEDIFF(wk, DATEADD(dd,-@@DATEFIRST,[StartDate]), DATEADD(dd,-@@DATEFIRST,[EndDate]))) AS [WorkingDays] 
FROM /*Your Table*/