创建数据库db6
create database db6 charset=utf8;
user db6;
# 创建班级表
mysql> create table class(cid int primary key auto_increment,caption varchar(50) not null unique); Query OK, 0 rows affected (0.15 sec) mysql> select * from class; Empty set (0.00 sec) mysql> insert into class(caption) values(‘三年二班‘),(‘一年三班‘),(‘三年一班‘); Query OK, 3 rows affected (0.00 sec) Records: 3 Duplicates: 0 Warnings: 0 mysql> select * from class; +-----+--------------+ | cid | caption | +-----+--------------+ | 2 | 一年三班 | | 3 | 三年一班 | | 1 | 三年二班 | +-----+--------------+ 3 rows in set (0.00 sec)
# 创建老师表
mysql> create table teacher(tid int primary key auto_increment,tname varchar(50) not null); Query OK, 0 rows affected (0.11 sec) mysql> insert into teacher(tname) values(‘李老师‘),(‘吴老师‘),(‘陈老师‘); Query OK, 3 rows affected (0.12 sec) Records: 3 Duplicates: 0 Warnings: 0 mysql> select * from teacher; +-----+-----------+ | tid | tname | +-----+-----------+ | 1 | 李老师 | | 2 | 吴老师 | | 3 | 陈老师 | +-----+-----------+ 3 rows in set (0.00 sec)
多对一关系建表
# 学生表与班级表建立关系
创建学生表
mysql> create table student( sid int primary key auto_increment, sname varchar(20) not null, gender enum(‘男‘,‘女‘) not null, class_id int not null, foreign key(class_id) references class(cid) on delete cascade on update cascade); Query OK, 0 rows affected (0.06 sec)
mysql> insert into student(sname,gender,class_id) values(‘小红‘,‘女‘,1),(‘小李‘,‘女‘,1),(‘小刚‘,‘男‘,2); Query OK, 3 rows affected (0.36 sec) Records: 3 Duplicates: 0 Warnings: 0 mysql> select * from student; +-----+--------+--------+----------+ | sid | sname | gender | class_id | +-----+--------+--------+----------+ | 1 | 小红 | 女 | 1 | | 2 | 小李 | 女 | 1 | | 3 | 小刚 | 男 | 2 | +-----+--------+--------+----------+ 3 rows in set (0.00 sec)
# 老师表和课程表建立关系
创建课程表
mysql> create table course( cid int primary key auto_increment, cname varchar(20) not null, tearch_id int not null,foreign key(tearch_id) references teacher(tid) on delete cascade on update cascade); Query OK, 0 rows affected (0.12 sec
插入记录 并查询
mysql> insert into course(cname,tearch_id) values(‘生物‘,1),(‘体育‘,1),(‘物理‘,2); Query OK, 3 rows affected (0.11 sec) Records: 3 Duplicates: 0 Warnings: 0 mysql> select * from course; +-----+--------+-----------+ | cid | cname | tearch_id | +-----+--------+-----------+ | 1 | 生物 | 1 | | 2 | 体育 | 1 | | 3 | 物理 | 2 | +-----+--------+-----------+ 3 rows in set (0.00 sec)
建立多对多关系
# 建立一张score表 与 学生表 课程表建立关系
mysql> create table score( sid int not null unique auto_increment, student_id int not null, corse_id int not null, number char(16) not null, foreign key(student_id) references student(sid) on delete cascade on update cascade, foreign key(corse_id) references course(cid) on delete cascade on update cascade, primary key(student_id,corse_id));
插入记录
mysql> insert into score(student_id,corse_id,number) values(1,1,‘60‘),(1,2,‘59‘),(2,2,‘100‘); Query OK, 3 rows affected (0.70 sec) Records: 3 Duplicates: 0 Warnings: 0 mysql> select * from score; +-----+------------+----------+--------+ | sid | student_id | corse_id | number | +-----+------------+----------+--------+ | 1 | 1 | 1 | 60 | | 2 | 1 | 2 | 59 | | 3 | 2 | 2 | 100 | +-----+------------+----------+--------+ 3 rows in set (0.00 sec)
原文地址:https://www.cnblogs.com/mingerlcm/p/9868437.html
时间: 2024-10-03 06:20:45