数据库表中多对多关系怎么设计？

(多对多关系） 

马克-to-win：Teacher表:两列id,name。

Studnet表: 三列：id,name，age

TeacherStudent表(关系表)：三列：id,tid,sid

create table TeacherStudent(id int not null,tid int not null,sid int not null);

2) teacher and student:（一个老师可能有多个学生，一个学生可能有多个老师）

qixy有两个学生：liyaohua and fuwenlong, huanglaosh老师有一个学生--->fuwenlong

INSERT INTO TeacherStudent (id,tid,sid) VALUES(1,1,1);

INSERT INTO TeacherStudent (id,tid,sid) VALUES(2,1,2);

INSERT INTO TeacherStudent (id,tid,sid) VALUES(3,2,2);

qixy的学生显示出来。

select * from Teacher t,Student s,TeacherStudent ts where t.name='qixy' and t.id=ts.tid and s.id=ts.sid;

+----+------+----+-----------+------+----+-----+-----+

| id | name | id | name      | age  | id | tid | sid |

+----+------+----+-----------+------+----+-----+-----+

|  1 | qixy |  1 | liyaohua  |   25 |  1 |   1 |   1 |

|  1 | qixy |  2 | fuwenlong |   26 |  2 |   1 |   2 |

+----+------+----+-----------+------+----+-----+-----+

huanglaosh的学生显示出来。

select * from Teacher t,Student s,TeacherStudent ts where t.name='huanglaosh' and t.id=ts.tid and s.id=ts.sid;

+----+------------+----+-----------+------+----+-----+-----+

| id | name       | id | name      | age  | id | tid | sid |

+----+------------+----+-----------+------+----+-----+-----+

|  2 | huanglaosh |  2 | fuwenlong |   26 |  3 |   2 |   2 |

+----+------------+----+-----------+------+----+-----+-----+

fuwenlong的老师显示出来。

select * from Teacher t,Student s,TeacherStudent ts where s.name='fuwenlong' and t.id=ts.tid and s.id=ts.sid;

+----+------------+----+-----------+------+----+-----+-----+

| id | name       | id | name      | age  | id | tid | sid |

+----+------------+----+-----------+------+----+-----+-----+

|  1 | qixy       |  2 | fuwenlong |   26 |  2 |   1 |   2 |

|  2 | huanglaosh |  2 | fuwenlong |   26 |  3 |   2 |   2 |

+----+------------+----+-----------+------+----+-----+-----+

参考一下以下游动的同等写法：（未来springJdbc或mybatisxxxxx的某种技术中也许用的着，因为它严格限制单表游动）

select name from Student where id in (select sid from TeacherStudent  where tid in (select id from Teacher where name='qixy')) ;

结果：

+-----------+

| name      |

+-----------+

| liyaohua  |

| fuwenlong |

+-----------+

更多请看下节：https://blog.csdn.net/qq_44591615/article/details/109205764