#一对多
# 先创建被关联表
create table dep(
id int primary key auto_increment,
name varchar(6),
comment varchar(30)
);
# 再创建关联表
create table employee(
id int primary key auto_increment,
name varchar(10),
gender varchar(5),
dep_id int,
foreign key(dep_id) references dep(id) on delete cascade on update cascade
);
#多对多: --其实就是建一个中间表,用于存放两个表的对应关系
create table author(
id int primary key auto_increment,
name varchar(10)
);
create table book(
id int primary key auto_increment,
name varchar(16)
);
create table author2book(
id int primary key auto_increment,
author_id int,
book_id int,
foreign key(author_id) references author(id) on delete cascade on update cascade,
foreign key(book_id) references book(id) on delete cascade on update cascade
);
# 一对一:
create table customer(
id int primary key auto_increment,
name varchar(16),
phone char(11)
);
create table student(
id int primary key auto_increment,
class varchar(10),
course varchar(16),
c_id int unique,
foreign key(c_id) references customer(id) on delete cascade on update cascade
);
105 表与表之间的关系
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转载自blog.csdn.net/qq_40808228/article/details/108369686
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