T-SQL get number of working days between 2 dates

Question

I want to calculate the number of working days between 2 given dates. For example if I want to calculate the working days between 2013-01-10 and 2013-01-15, the result must

Answer 1

Here's a simple function that counts working days not including Saturday and Sunday (when counting holidays isn't necessary):

CREATE FUNCTION dbo.udf_GetBusinessDays (

@START_DATE DATE,
@END_DATE DATE

)
RETURNS INT
WITH EXECUTE AS CALLER
AS

BEGIN

 DECLARE @NUMBER_OF_DAYS INT = 0;
 DECLARE @DAY_COUNTER INT = 0;
 DECLARE @BUSINESS_DAYS INT = 0;
 DECLARE @CURRENT_DATE DATE;
 DECLARE @DAYNAME NVARCHAR(9)

 SET @NUMBER_OF_DAYS = DATEDIFF(DAY, @START_DATE, @END_DATE);

 WHILE @DAY_COUNTER <= @NUMBER_OF_DAYS
 BEGIN

    SET @CURRENT_DATE = DATEADD(DAY, @DAY_COUNTER, @START_DATE)
    SET @DAYNAME = DATENAME(WEEKDAY, @CURRENT_DATE)
    SET @DAY_COUNTER += 1

    IF @DAYNAME = N'Saturday' OR @DAYNAME = N'Sunday'
    BEGIN
        CONTINUE
    END
    ELSE
    BEGIN
        SET @BUSINESS_DAYS += 1
    END
 END

 RETURN @BUSINESS_DAYS
END
GO