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

 DECLARE @TotalDays INT,@WorkDays INT
 DECLARE @ReducedDayswithEndDate INT
 DECLARE @WeekPart INT
 DECLARE @DatePart INT

 SET @TotalDays= DATEDIFF(day, @StartDate, @EndDate) +1
 SELECT @ReducedDayswithEndDate = CASE DATENAME(weekday, @EndDate)
  WHEN 'Saturday' THEN 1
  WHEN 'Sunday' THEN 2
  ELSE 0 END 
 SET @TotalDays=@TotalDays-@ReducedDayswithEndDate
 SET @WeekPart=@TotalDays/7;
 SET @DatePart=@TotalDays%7;
 SET @WorkDays=(@WeekPart*5)+@DatePart

 RETURN @WorkDays