mysql 的连接

1.内连接 INNER JOIN

select * from data inner join users on data.id = users.id;

2.左连接 LEFT JOIN

select * from data left join users on data.id = users.id

就算右侧数据比左侧少，也会将左侧的数据全部打印出来。

3.右连接 RIGHT JOIN

和左连接同理

select * from data right join users on data.id = users.id