ALTER FUNCTION  [dbo].[GetWeekDay]
( 
@Year INT, @Month INT ,@Day INT 
)
RETURNS INT 
AS
BEGIN

 DECLARE @date DATETIME= DATEFROMPARTS(@Year,@Month,@Day);
 DECLARE @weekday INT =0;
 --select @@datefirst
 --SELECT alias, * from master..syslanguages
 --SELECT DATEPART(WEEKDAY,'2018-11-17')
 IF
 
 @@DATEFIRST =7---從週日開始到週六  1,2,3,4,5,6,7
 BEGIN 
 SET @weekday= 7-(8- DATEPART(WEEKDAY,@date) )%7  ;
 END ELSE  -----1---從週一開始到週日  1,2,3,4,5,6,7
 BEGIN 
 SET @weekday= DATEPART(WEEKDAY,@date) ;
 END 
--SELECT 7-(8- DATEPART(WEEKDAY,'2018-11-23') )%7 
--SELECT 7-(8- DATEPART(WEEKDAY,'2018-11-24') )%7
 

--SELECT 7-(8- DATEPART(WEEKDAY,'2018-11-25') )%7
--SELECT dbo.GetWeekDay(2018,11,23)
--SELECT dbo.GetWeekDay(2018,11,24)
--SELECT dbo.GetWeekDay(2018,11,25)
--SELECT dbo.GetWeekDay(2018,11,26)
 --SELECT dbo.GetWeekDay(2018,11,20)
 --SELECT dbo.GetWeekDay(2018,11,21)
 --SELECT dbo.GetWeekDay(2018,11,22)
 

 --SELECT dbo.GetWeekDay(2018,11,23)
 --SELECT dbo.GetWeekDay(2018,11,24)
 --SELECT dbo.GetWeekDay(2018,11,25)
 --SELECT dbo.GetWeekDay(2018,11,26)
 RETURN @weekday 
END