数据库表中一对多关系怎么设计?
Database Design(数据库设计)
马克-to-win:
(一对多:one-to-many)
1) teacher and student.
(teacher表:两列id(主键),name。
pupil表: 三列:id(主键),name,tid(外键))
举例: Teacher "qixy" has two students: liyaohua,fuwenlong. Teacher "huanglaosh" has two students: mashuai,jiaxiaohu.
create table pupil(id int not null,name char(10),tid int);
create table teacher(id int not null,name char(10));
INSERT INTO pupil (id,name,tid) VALUES(1,'liyaohua',1);
INSERT INTO pupil (id,name,tid) VALUES(2,'fuwenlong',1);
INSERT INTO pupil (id,name,tid) VALUES(3,'mashuai',2);
INSERT INTO pupil (id,name,tid) VALUES(4,'jiaxiaohu',2);
INSERT INTO teacher (id,name) VALUES(1,'qixy');
INSERT INTO teacher (id,name) VALUES(2,'huanglaosh');
select * from pupil,teacher where tid=teacher.id and teacher.name='qixy';
+----+-----------+------+----+------+
| id | name | tid | id | name |
+----+-----------+------+----+------+
| 1 | liyaohua | 1 | 1 | qixy |
| 2 | fuwenlong | 1 | 1 | qixy |
+----+-----------+------+----+------+