将周末日期改为周五

create  function dbo.WeekToFriday( @date char(10))
returns char(10)
as
begin
if((select datename(weekday,@date))= '星期六' or (select datename(weekday,@date))= 'Saturday' )
   set @date=dateadd(day,-1,@date )
   set @date=convert(char(4),(year('11  9 2007')))+'-'+convert(char(2),(month('11  9 2007')))+'-'+convert(char(2),(day('11  9 2007')))
   return (@date)
if((select datename(weekday,@date))= '星期日' or (select datename(weekday,@date))= 'Sunday')
    set @date=dateadd(day,-2,@date )
    set @date=convert(char(4),(year('11  9 2007')))+'-'+convert(char(2),(month('11  9 2007')))+'-'+convert(char(2),(day('11  9 2007')))
    return (@date)
 
end

GO

测试语句

select dbo.WeekToFriday('2007-11-10')

结果

2007-11-9