CREATE FUNCTION [dbo].[CalculateBusinessDays]
(
    @StartDate DATE,
    @EndDate DATE
)
RETURNS INTEGER
AS
BEGIN
    IF @EndDate IS NULL
        SELECT @EndDate = GETDATE()
    RETURN  CONVERT(INTEGER,
         (DATEDIFF(dd, @StartDate, @EndDate) + 1)
       - (DATEDIFF(wk, @StartDate, @EndDate) * 2)
       - (CASE WHEN DATENAME(dw, @StartDate) = 'Sunday' THEN 1 ELSE 0 END)
       - (CASE WHEN DATENAME(dw, @EndDate) = 'Saturday' THEN 1 ELSE 0 END)
       - ISNULL((SELECT COUNT(*) FROM tblHoliDays
                 WHERE @StartDate <= Holiday AND @EndDate >= Holiday), 0))
END