mssql和mysql区别_MSSQL使用update join更新记录示例

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数据准备

 代码如下

create table tab1(name nvarchar(20),gold int)
create table tab2(name nvarchar(20),gold int)
--data
insert into tab1 values("user1",10)
insert into tab1 values("user2",10)
insert into tab2 values("user1",20)

2.update join更新记录

 代码如下

update tab1 set gold=t1.gold+t2.gold from tab1 t1 inner join tab2 t2 on t1.name=t2.name

说明：两张表的数据一定要是一对一关系，否则更新结果可能不明确。

网上整理的两个句话

1.加回原消费金额

 代码如下 UPDATE e SET e.money = e.money + d.amount
       FROM employee e
       INNER JOIN (SELECT empid,amount=sum(amount) FROM deleted  WHERE rechargeable=1  GROUP BY empid) d  ON d.empid=e.id

      
2.扣除新消费金额

 代码如下

UPDATE e SET e.money = e.money - i.amount
       FROM employee e
       INNER JOIN (SELECT empid,amount=sum(amount) FROM inserted WHERE rechargeable=1 GROUP BY empid) i ON i.empid=e.id

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