SQL Update多表关联修改

1、SqlServer

UPDATE a SET a.a1=b.b1,a.a2=b.b2 FROM A a
  INNER JOIN B b ON a.a3=b.b3

Update 后面跟 别名，From后的条件就可以跟Select一样来写了

2、Oracle

UPDATE A a  SET (a.a1,a.a2)=(SELECT b.b1,b,b2 FROM B b WHERE b.b3=a.a3)

3、MySql

UPDATE A a , B b SET a.a1 = b.b1 , a.a2 = b.b2 WHERE a.a3 = b.b3