Heim >Backend-Entwicklung >PHP-Tutorial >SQL语句问题,关联查询,一对多
比如老师和学生表,一个老师对应多个学生。想查出来老师A和他对应的学生1,2,3,老师B和他对应的4,5,6.
select * from 学生表 a,教师表 b,教师学生关系表 c where a.studentid = c.studentid and b.teacherid = teacherid and b.teacherid = 你要查的老师id
表结构是怎样的?
table teacher
id name
1 A
2 B
table student
id tid
1 1
2 1
3 1
4 2
5 2
6 2
A老师的学生
select * from student where tid=1;
B老师的学生
select * from student where tid=2;
或者 select a.*,b.name from student as a left join teacher as b on a.tid = b.id order by a.tid;
老师有个ID 查询 符合这个ID 条件的所有学生...