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

Here is a version that works well (I think). Holiday table contains Holiday_date columns that contains holidays your company observe.

DECLARE @RAWDAYS INT

   SELECT @RAWDAYS =  DATEDIFF(day, @StartDate, @EndDate )--+1
                    -( 2 * DATEDIFF( week, @StartDate, @EndDate ) )
                    + CASE WHEN DATENAME(dw, @StartDate) = 'Saturday' THEN 1 ELSE 0 END
                    - CASE WHEN DATENAME(dw, @EndDate) = 'Saturday' THEN 1 ELSE 0 END 

   SELECT  @RAWDAYS - COUNT(*) 
     FROM HOLIDAY NumberOfBusinessDays
    WHERE [Holiday_Date] BETWEEN @StartDate+1 AND @EndDate