Question

我有一个Staging和Master表，其中包含这样的列第1步：

Create table Staging(
    ID varchar(10) not null, 
    name varchar(100) not null, 
    createddate datetime not null
)

第2步：

insert into Staging('1','Amy','2014-01-01');

第3步：

Create table Master(
    ID varchar(10) not null, 
    name varchar(100) not null, 
    createddate datetime not null,
    verifieddate datetime not null
)

第4步：

insert into master(
    select id,
            name,
            createddate,
            createddate 
    from    staging s 
    left outer join master on m on m.id=s.id where m.id is null);

第2天：

delete from Staging;
insert into Staging('1','Amy','2014-02-01');
insert into Staging('2','Binny','2014-01-01');

我运行第4步，将ID = 2插入Master。我想通过保持createddate相同来更新ID = 1，但验证日期应更改为2014-02-01。所以，我写了这样的更新声明

update Master set VerifiedDate = 
(case when i.verifieddate < a.createddate then a.createddate end) 
      FROM Staging a inner join 
      Master i 
     on i.id=a.[ID] where i.verifieddate < a.createddate

它不起作用。任何建议。

Answer 1

理论上，您应该能够使用UPDATE语句来执行此操作，如：

UPDATE m

SET         VerifiedDate = s.CreatedDate

FROM        Master AS m

INNER JOIN  Staging AS s
    ON      m.Id = s.Id
    AND     s.CreatedDate > m.VerifiedDate

SqlServer Update Case语句

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