Switch: SQL Server user-defined function: count the number of workdays between two dates

Create function kmes. workDay_f (@ dt_begin datetime, @ dt_end datetime) RETURNS intASBEGIN DECLARE @ workday int, @ I int, @ bz bit, @ dt datetime set @ dt_begin = convert (datetime, convert (nvarchar (32), @ dt_begin, 23) set @ dt_end = convert (datetime, convert (nvarchar (32), @ dt_end, 23 )) IF @ dt_begin> @ dt_end SELECT @ bz = 1, @ dt = @ dt_begin, @ dt_begin = @ dt_end, @ dt_end = @ dt else set @ bz = 0 SELECT @ I = DATEDIFF (Day, @ dt_begin, @ dt_end), @ workday = @ I/7*5, @ dt_begin = DATEADD (Day, @ I/7*7, @ dt_begin) WHILE @ dt_begin <@ dt_end BEGIN SELECT @ workday = CASE WHEN (@ DATEFIRST + DATEPART (Weekday, @ dt_begin)-1) % 7 BETWEEN 1 AND 5 THEN @ workday + 1 ELSE @ workday END, @ dt_begin = @ dt_begin + 1 end return (case when @ bz = 1 THEN-@ workday ELSE @ workday END) ENDGO