1、先取出两张表主键值相同的数据
select * from table1 where primary_column in (select primary_column from table2); -- 表m
select * from table2 where primary_column in (select primary_column from table1); --表n
2、做差求并集的结果就是两张表主键相同而其它列存在差异的所有行
select * from (
select * from m
minus
select * from n)
union
(select * from n
minus
select * from m);