MySQL的几种join方法

左链接

mysql> select * from t1 left join t2 on t1.id = t2.id;

右链接

mysql> select * from t1 right join t2 on t1.id =t2.id;
内链接

mysql> select * from t1 inner join t2 on t1.id = t2.id;
左独有

mysql> select * from t1 left join t2 on t1.id = t2.id where t2.id is null;
右独有

mysql> select * from t1 right join t2 on t1.id = t2.id where t1.id is  null;
全连接

mysql> select * from t1 left join t2 on t1.id = t2.id
    -> union 
    -> select * from t1 right join t2 on t1.id = t2.id;
并集去交集

mysql> select * from t1 left join t2 on t1.id = t2.id where t2.id is null
    -> union 
    -> select * from t1 right join t2 on t1.id = t2.id where t1.id is null;