T-SQL: DATEDIFF() between working dates

Function for see the difference between dates in working days.

CREATE FUNCTION dbo.DifferenceWorkingDays (@Data1 AS DATE, @Data2 AS DATE)

RETURNS INT

AS

BEGIN

    DECLARE @DataVar as DATETIME, @Giorni as INT
    SET @DataVar=@Data2
    SET @Giorni=0

    --remove a day at time until reach the day requested    
    WHILE @DataVar > @Data1

    BEGIN
       SET @DataVar=DATEADD(d,-1,@DataVar)

       --if saturday or sunday remove another day without update the counter
       IF DATEPART(dw,@DataVar)= 1 SET @DataVar=DATEADD(d,-1,@DataVar)
       IF DATEPART(dw,@DataVar)= 7 SET @DataVar=DATEADD(d,-1,@DataVar)

       SET @Giorni=@Giorni+1   
    END

    RETURN @Giorni

END

GO

You can call it instead DATEDIFF() if you need the working day difference.

SELECT Database.dbo.DifferenceWorkingDays(GETDATE(), '2016-06-24')

To skip also holiday outside saturday and sundays, you have to add a custom table with this dates and include it in the function.
If you want to add working days to a date, take a look here.