zoukankan      html  css  js  c++  java
  • 2020python练习——表的关系

    @2020.5.5

    练习:账号信息表,用户组,主机表,主机组

    #用户表
    create table user(
    id int not null unique auto_increment,
    username varchar(20) not null,
    password varchar(50) not null,
    primary key(username,password)
    );
    
    #用户组表
    create table usergroup(
    id int primary key auto_increment,
    groupname varchar(20) not null unique
    );
    
    #主机表
    create table host(
    id int primary key auto_increment,
    ip char(15) not null unique default '127.0.0.1'
    );
    
    #业务线表
    create table business(
    id int primary key auto_increment,
    business varchar(20) not null unique
    );
    
    #建关系:user与usergroup
    
    create table user2usergroup(
    id int not null unique auto_increment,
    user_id int not null,
    group_id int not null,
    primary key(user_id,group_id),
    foreign key(user_id) references user(id),
    foreign key(group_id) references usergroup(id)
    );
    
    #建关系:host与business
    create table host2business(
    id int not null unique auto_increment,
    host_id int not null,
    business_id int not null,
    primary key(host_id,business_id),
    foreign key(host_id) references host(id),
    foreign key(business_id) references business(id)
    );
    
    #建关系:user与host
    create table user2host(
    id int not null unique auto_increment,
    user_id int not null,
    host_id int not null,
    primary key(user_id,host_id),
    foreign key(user_id) references user(id),
    foreign key(host_id) references host(id)
    );
  • 相关阅读:
    Arduino uno 教程~持续更新~
    Arduino uno LED灯实验
    Arduino uno 引脚说明
    面包板的使用
    数量经济学推荐的Julia教程
    已知一点经纬度和距离,方位角;求另外一点的经纬度
    a recipe kindly provided by Dimas for kikuchi
    发现了拯救“文献多的一团麻”的工具
    matlab中diff的用法
    matlabR2017安装
  • 原文地址:https://www.cnblogs.com/bigorangecc/p/12831161.html
Copyright © 2011-2022 走看看