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  • mysql 建立表之间关系 一对一 练习2

    创建db5数据库

    create database db5 charset=utf8;

    use db5;

    例二:一个管理员唯一对应一个用户
        用户表:
        id user  password
         1  egon    xxxx
         2  alex    yyyy
    
    创建用户表
    mysql> create table user(
    id int primary key auto_increment,
    user varchar(50) not null,
    password varchar(50) not null); 
    Query OK, 0 rows affected (0.12 sec)
    
    
    

    插入用户信息

    mysql> insert into user(user,password) values('alex','123'),('mike','1234'),('jack','123');
    Query OK, 3 rows affected (0.01 sec)
    Records: 3  Duplicates: 0  Warnings: 0
    
    mysql> select * from user;
    +----+------+----------+
    | id | user | password |
    +----+------+----------+
    |  1 | alex | 123      |
    |  2 | mike | 1234     |
    |  3 | jack | 123      |
    +----+------+----------+
    3 rows in set (0.00 sec)


    管理员表: fk+unique id user_id password 1 1 xxxxx 2 2 yyyyy


    创建管理员表
    mysql> create table Administrator(
    id int primary key auto_increment,
    user_id int unique,
    password varchar(50) not null,
    foreign key(user_id) references user(id)
    on delete cascade 
    on update cascade);
    Query OK, 0 rows affected (0.20 sec)
    
    
    

    插入记录

    mysql> insert into Administrator(user_id,password) values(1,'123'),(2,'1234'),(3,'123');
    Query OK, 3 rows affected (0.01 sec)
    Records: 3  Duplicates: 0  Warnings: 0
    mysql> select * from Administrator;
    +----+---------+----------+
    | id | user_id | password |
    +----+---------+----------+
    |  1 |       1 | 123      |
    |  2 |       2 | 1234     |
    |  3 |       3 | 123      |
    +----+---------+----------+
    3 rows in set (0.00 sec)
     
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  • 原文地址:https://www.cnblogs.com/mingerlcm/p/9866510.html
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