设计表：多张表存储学生成绩及各种信息

create table class
(
code varchar(20) primary key,
name varchar(20) 

);

create table kecheng
(
code varchar(20) primary key,
name varchar(20) 

);


create table teacher
(
code varchar(20) primary key,
name varchar(20) 

);


create table tkecheng
(
    ids int auto_increment primary key,
    tcode varchar(20),
    kcode varchar(20),
    foreign key (tcode) references teacher(code),
    foreign key (kcode) references kecheng(code)
);

create table student
(
    code varchar(20) primary key,
    name varchar(20),
    sex bit,
    age int,
    class varchar(20),
    foreign key (class) references class(code)    
);

create table chengji
(
    isd int auto_increment primary key,
    scode varchar(20),
    kcode varchar(20),
    degree float,
    foreign key (scode) references student(code),
    foreign key (kcode) references kecheng(code)

);