MySQL表操作练习

题目: 

　　创建班级,学生,老师,课程,以及成绩表;

　　其中表关系有一对多,和多对多关系.表的关系是确定使用双边分析发.比如,一个班级可以对应多个学生,但一个学生不可以对应多个班级,这就是一对多关系表.一个学生可以对应多门课程,一个课程可以对于多个学生,这就是表的多对多关系.

         

   

'''
创建班级表, 学生表, 老师表, 课程表,成绩表
# 创建班级表class
create table class(
    id int primary key auto_increment,
    caption varchar(16),
    unique(id,caption)
    );
# 插入班级信息
insert into class(caption) values('三年级二班'),
    ('一年级三班'),
    ('三年级一班');
# 查看班级表信息和数据
desc class;
select *from class;

# 创建学生列表student
create table student(
    id int primary key auto_increment,
    name varchar(16),
    gender enum('boy', 'girl') default 'boy',  # enum前不加数据类型
    class_id int,
    foreign key(class_id) references class(id)
    on update cascade
    on delete cascade
    );
# 插入学生数据
insert into student(name,gender,class_id) values('峰','boy',2),
    ('洋','boy',3),
    ('红','girl',1),
    ('雪','girl',3),
    ('林','girl',1),
    ('空','boy',1);
    
# 查看学生数据
describe student; 
select *from student;   

# 创建教师列表teacher
create table teacher(
    id int primary key auto_increment,
    name varchar(32)
    );
insert into teacher(name) values('李叔同'),
    ('叶平'),
    ('冯友兰');
# 查看表
show create table teacher;
select *from teacher;

# 课程表course
create table course(
    id int primary key auto_increment,
    name varchar(16),
    teacher_id int,
    foreign key(teacher_id) references teacher(id)
    on update cascade
    on delete cascade
    );
    
insert into course(name,teacher_id) values('生物',2),
    ('体育',2),
    ('哲学',3),
    ('艺术',2);
# 查看表
show table course;
select *from course;

创建成绩表
create table score(
    id int primary key auto_increment,
    student_id int,
    foreign key(student_id) references student(id)
    on update cascade
    on delete cascade,
    course_id int,
    foreign key(course_id) references course(id)
    on update cascade
    on delete cascade,
    number int
    );
insert into score(student_id,course_id,number) values(1,2,59),
    (1,2,79),
    (1,3,89),
    (2,1,90),
    (2,2,100),
    (2,1,98),
    (3,2,88),
    (3,3,96),
    (4,3,96);
查看表:
desc score;
select *from score  
    
'''
'''
select *from class;
select *from teacher;
select *from student;
select *from teacher;
select *from course;
select *from score;

'''