我有一個表列[加載日期]，我想添加一列[更新日期] ....在SQL Server

Question

我有一個表[Load date]列，我想添加一列[Updated Date]週一至週五數據與[Load Date]相同，但Sun-Sat作爲星期一的數據[Load Date] .....我怎麼能在SQL Server中做到這一點？

Answer 1

CREATE TABLE table3 
( 
orderdate datetime 
) 


CREATE FUNCTION dbo.getupdateddate(@orderdate datetime) 
RETURNS datetime 
AS 
BEGIN 
declare @updateddate datetime 
    if datepart(weekday,@orderdate) in (1,2,3,4,5) 
    set @updateddate=@orderdate; 
    else 
    select top 1 @updateddate= orderdate from table3 
where datepart  (weekday,@orderdate) =2 
    order by orderdate desc 
    return @updateddate 

END 

ALTER TABLE table3 
ADD updateddate AS dbo.getupdateddate(orderdate) 

select @@DATEFIRST--7 
insert into table3 
(orderdate) 
select getdate() 

select * from table3 


    orderdate     updateddate 
2016-04-12 00:29:14.343 2016-04-12 00:29:14.343 

幾點要注意：
1.設置DATEFIRST指定一週的第一天。美國英語默認爲7，星期日。
2.如果週一沒有日子，您可能需要添加空值