46数据库03——课后练习

mysql> use day46
Database changed
mysql> create table user(
    -> id int not null unique auto_increment,
    -> username varchar(20) not null,
    -> password varchar(50) not null,
    -> primary key(username,password)
    -> );
Query OK, 0 rows affected (0.02 sec)

mysql> create table usergroup(
    -> id int primary key auto_increment,
    -> groupname varchar(20) not null unique
    -> );
Query OK, 0 rows affected (0.02 sec)

mysql> create table host(
    -> id int primary key auto_increment,
    -> ip char(15) not null unique default ‘127.0.0.1‘
    -> );
Query OK, 0 rows affected (0.01 sec)

mysql> create table business(
    -> id int primary key auto_increment,
    -> business varchar(20) not null unique
    -> );
Query OK, 0 rows affected (0.01 sec)

mysql> 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)
    -> );
Query OK, 0 rows affected (0.01 sec)

mysql> 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)
    -> );
Query OK, 0 rows affected (0.01 sec)

mysql> 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)
    -> );
Query OK, 0 rows affected (0.01 sec)

mysql> show tables;
+-----------------+
| Tables_in_day46 |
+-----------------+
| business        |
| host            |
| host2business   |
| user            |
| user2host       |
| user2usergroup  |
| usergroup       |
+-----------------+
7 rows in set (0.00 sec)

#班级表
mysql> create table class( 
    -> cid int primary key auto_increment,
    -> caption char not null
    -> );
Query OK, 0 rows affected (0.01 sec)
#学生表
mysql> create table student(
    -> sid int primary key auto_increment,
    -> sname char(20) not null,
    -> gender enum(‘male‘,‘female‘)default ‘male‘
    -> class_id int ,
    -> foreign key(class_id) references class(id)
    -> on update cascade 
    -> on delete cascade
    -> ); 
Query OK, 0 rows affected (0.01 sec) 
#老师表
mysql> create table teacher(
    -> tid int primary key auto_increment,
    -> tname char(20) not null
    -> );
Query OK, 0 rows affected (0.01 sec)
#课程表 
mysql> create table course( 
    -> cid int primary key auto_increment, 
    -> cname char(50), 
    -> teacher_id int , 
    -> foreign key(teacher_id) references teacher(id) 
    -> on update cascade 
    -> on delete cascade
    -> ); 
Query OK, 0 rows affected (0.01 sec)
#成绩表
mysql> create table scores(
    -> id int primary key auto_increment,
    -> student_id int not null,
    -> course_id int not null,
    -> number float not null
    -> );
Query OK, 0 rows affected (0.01 sec)
#建成绩关联表

mysql> create table stu2course(
    -> id int not null,
    -> stu_id int not null,
    -> cs_id int not null,
    -> primary key(stu_id,cs_id),
    -> foreign key(stu_id) references student(id)
    -> on update cascade 
    -> on delete cascade,
    -> foreign key(cs_id) references course(id)
    -> on update cascade 
    -> on delete cascade
    -> );