MSSQL statement used to calculate the number of working days between two dates

Copy codeThe Code is as follows: if exists (select * from dbo. sysobjects where id = object_id (n' [dbo]. [f_WorkDay] ') and xtype in (n'fn', n'if', n'tf '))
Drop function [dbo]. [f_WorkDay]
GO
-- Calculate the working days of two different dates
Create function f_WorkDay (
@ Dt_begin datetime, -- Calculation start date
@ Dt_end datetime -- end date of Calculation
) RETURNS int
AS
BEGIN
Declare @ I int
Select @ I = abs (datediff (dd, @ dt_begin, @ dt_end ))
Declare @ t table (dt datetime)
If @ dt_begin> @ dt_end
Insert @ t select dateadd (dd, number, @ dt_end) from master... spt_values
Where number <= @ I and type = 'P'
Else
Insert @ t select dateadd (dd, number, @ dt_begin) from master .. spt_values
Where number <= @ I and type = 'P'
Return (select count (*) from @ t where (datepart (weekday, dt) + @ datefirst-1) % 7 between 1 and 5)
END
GO
Select dbo. f_WorkDay ('2017-10-10 ', '2017-10-1 ')
/*
-----------
7
(A data column is affected)
*/
If exists (select * from dbo. sysobjects where id = object_id (n' [dbo]. [f_WorkDay] ') and xtype in (n'fn', n'if', n'tf '))
Drop function [dbo]. [f_WorkDay]
GO
-- Calculate the working days of two different dates
Create function f_WorkDay (
@ Dt_begin datetime, -- Calculation start date
@ Dt_end datetime -- end date of Calculation
) RETURNS int
AS
BEGIN
DECLARE @ workday int, @ I int, @ bz bit, @ dt datetime
Set @ workday = 0
IF @ dt_begin> @ dt_end
SELECT @ bz = 1, @ dt = @ dt_begin, @ dt_begin = @ dt_end, @ dt_end = @ dt
ELSE
SET @ bz = 0
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)
END
GO
Select dbo. f_WorkDay ('2017-10-10 ', '2017-10-1 ')
/*
-----------
-7
*/