Basic Join 基本交，Cross Join 叉交，INNER JOIN 内交，OUTER JOIN 外交，Left join 左交，Right join 右交，Full join全交都是什么？

Basic Join Operation--comma-separated join(叉乘，都乘到N*M,N,M分别是两个表的条数)
马克-to-win：  select * from register, student;

Cross Join(叉乘，都乘到N*M,N,M分别是两个表的条数)---same as comma-separated join

select * from register CROSS JOIN student;

select r.name, s.name,s.age from register r CROSS JOIN student s where r.id = s.id AND s.age >20;

INNER JOIN

交叉联接的作用同内联接一样。例如，下面的 Transact-SQL 查询得到相同的结果集： 

select * from register INNER JOIN student;

select r.name, s.name,s.age from register r INNER JOIN student s on r.id = s.id AND s.age >20;

 

OUTER JOIN