Mysql--链接查询

链接查询，用于多个表查询

inner join …on 内连接 两张表中有共同对应的信息，取交集
查询能够对应班级的学生以及班级信息

select * from student inner join classes on student.cls_id=classes.id;

查询显示姓名和班级

select s.name,c.name from student as s inner join classes as c on s.cls_id=c.id;//s.*表示student所有信息

查询 能够对应的班级的学生以及班级名称，按照班级进行排序

select s.*,c.name from student as s inner join classes as c where s.cls_id=c.id order by c.name desc;

左链接 left join…on,以左边的表为基准

右链接 right join …on