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 know this is an old question but I needed a formula for workdays excluding the start date since I have several items and need the days to accumulate correctly.

None of the non-iterative answers worked for me.

I used a defintion like

Number of times midnight to monday, tuesday, wednesday, thursday and friday is passed

(others might count midnight to saturday instead of monday)

I ended up with this formula

SELECT DATEDIFF(day, @StartDate, @EndDate) /* all midnights passed */
     - DATEDIFF(week, @StartDate, @EndDate) /* remove sunday midnights */
     - DATEDIFF(week, DATEADD(day, 1, @StartDate), DATEADD(day, 1, @EndDate)) /* remove saturday midnights */