摘要： 1. join/inner join / ,--内连接select * from A join B on ...;<==>select * from A inner join B on ...;<==>select * from A, B where ...;将同时满足条件的结果查询出来（即取交集）2. left join/left outer join--左连接select * from A left join B on ...;以左边表A为准，即使on条件不满足，左边表A的数据也会被查询出来。3. right join/right outer join--右连接se 阅读全文