MySQL 多表结构的创建与分析

Posted 2021-01-28 z1115230598

=====================多对一=====================
create table press(
id int primary key auto_increment,
name varchar(20)
);

create table book(
id int primary key auto_increment,
name varchar(20),
press_id int not null,
foreign key(press_id) references press(id)
on delete cascade
on update cascade
);


insert into press(name) values
(‘北京工业地雷出版社‘),
(‘人民音乐不好听出版社‘),
(‘知识产权没有用出版社‘)
;

insert into book(name,press_id) values
(‘九阳神功‘,1),
(‘九阴真经‘,2),
(‘九阴白骨爪‘,2),
(‘独孤九剑‘,3),
(‘降龙十巴掌‘,2),
(‘葵花宝典‘,3)
;

sql示例

多对一

create table author(
id int primary key auto_increment,
name varchar(20)
);


#这张表就存放作者表与书表的关系，即查询二者的关系查这表就可以了
create table author2book(
id int not null unique auto_increment,
author_id int not null,
book_id int not null,
constraint fk_author foreign key(author_id) references author(id)
on delete cascade
on update cascade,
constraint fk_book foreign key(book_id) references book(id)
on delete cascade
on update cascade,
primary key(author_id,book_id)
);


#插入四个作者，id依次排开
insert into author(name) values(‘egon‘),(‘alex‘),(‘yuanhao‘),(‘wpq‘);

#每个作者与自己的代表作如下
egon: 
九阳神功
九阴真经
九阴白骨爪
独孤九剑
降龙十巴掌
葵花宝典
alex: 
九阳神功
葵花宝典
yuanhao:
独孤九剑
降龙十巴掌
葵花宝典
wpq:
九阳神功


insert into author2book(author_id,book_id) values
(1,1),
(1,2),
(1,3),
(1,4),
(1,5),
(1,6),
(2,1),
(2,6),
(3,4),
(3,5),
(3,6),
(4,1)
;

sql示例

多对多

create table customer(
    -> id int primary key auto_increment,
    -> name varchar(20) not null,
    -> qq varchar(10) not null,
    -> phone char(16) not null
    -> );

create table student(
    -> id int primary key auto_increment,
    -> class_name varchar(20) not null,
    -> customer_id int unique, #该字段一定要是唯一的
    -> foreign key(customer_id) references customer(id) #外键的字段一定要保证unique
    -> on delete cascade
    -> on update cascade
    -> );

#增加客户
mysql> insert into customer(name,qq,phone) values
    -> (‘韩蕾‘,‘31811231‘,13811341220),
    -> (‘杨澜‘,‘123123123‘,15213146809),
    -> (‘翁惠天‘,‘283818181‘,1867141331),
    -> (‘杨宗河‘,‘283818181‘,1851143312),
    -> (‘袁承明‘,‘888818181‘,1861243314),
    -> (‘袁清‘,‘112312312‘,18811431230)

mysql> #增加学生
mysql> insert into student(class_name,customer_id) values
    -> (‘脱产1班‘,3),
    -> (‘周末1期‘,4),
    -> (‘周末1期‘,5)
    -> ;

sql示例

一对一