很绕,绕得有些晕更新:update b set 字段2 = (select 字段2 from a where a.字段1 = b.字段1) 其实你用不着更新,b的字段2可以省select b.字段1 ,a.字段2 from a inner join b on a.字段1=b.字段1
update bset 字段2 = (select 字段2 from A WHERE A.字段1 = B.字段1)