MySQL |*|#8212; 练习题_mysql if语句

一. 表关系

① 创建如下表,并创建相关约束.

# 创建班级表
create table class (
cid int primary key not null auto_increment,
caption varchar(20) not null
);

# 创建老师表
create table teacher (
tid int primary key not null auto_increment,
tname varchar(20) not null
);

# 创建学生表
create table student (
sid int primary key not null auto_increment,
sname varchar(20) not null,
gender enum("男", "女"),
class_id int not null,
constraint fk_student_class foreign key(class_id) references class(cid)
on delete cascade
on update cascade
);

# 创建课程表
create table course (
cid int primary key not null auto_increment,
cname varchar(20) not null,
teach_id int not null,
constraint fk_course_teacher foreign key(teach_id) references teacher(tid)
on delete cascade
on update cascade
);

# 创建成绩表
create table score(
sid int primary key not null auto_increment,
student_id int not null,
course_id int not null,
number int not null,
constraint fk_score_student foreign key(student_id) references student(sid)
on delete cascade
on update cascade,
constraint fk_score_course foreign key(course_id) references course(cid)
on delete cascade
on update cascade
);

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