创建db5数据库
create database db5 charset=utf8;
use db5;
例一:一个用户只有一个博客
用户表:
id name
1 mike
2 alex
3 jack
mysql> create table user(id int primary key auto_increment,name varchar(50) not null); Query OK, 0 rows affected (0.07 sec)
插入用户记录
mysql> insert into user(name) values('mike'),('alex'),('jack'); Query OK, 3 rows affected (0.01 sec) Records: 3 Duplicates: 0 Warnings: 0 mysql> select * from user; +----+------+ | id | name | +----+------+ | 1 | mike | | 2 | alex | | 3 | jack | +----+------+ 3 rows in set (0.00 sec)
博客表
fk+unique
id url name_id
1 xxxx 1
2 yyyy 3
3 zzz 2
mysql> create table blog(id int primary key auto_increment,
url varchar(50) not null,
name_id int unique,
foreign key(name_id) references user(id)
on delete cascade
on update cascade
); Query OK, 0 rows affected (0.13 sec)
插入记录
mysql> insert into blog(url,name_id) values('xxx',1),('yyyy',3),('zzz',2); Query OK, 3 rows affected (0.12 sec) Records: 3 Duplicates: 0 Warnings: 0 mysql> select * from blog; +----+------+---------+ | id | url | name_id | +----+------+---------+ | 1 | xxx | 1 | | 2 | yyyy | 3 | | 3 | zzz | 2 | +----+------+---------+ 3 rows in set (0.00 sec)