搭建一个简易的成绩管理系统的数据库

create database gradesystem;
use gradesystem;

create table student
(
    sid int NOT NULL AUTO_INCREMENT,
    sname varchar(21) NOT NULL,
    gender enum('male', 'female') NOT NULL,
    PRIMARY KEY(sid)
);

create table course
(
    cid int(10) NOT NULL AUTO_INCREMENT,
    cname varchar(21) NOT NULL,
    PRIMARY KEY(cid)
);

create table mark
(
    mid int NOT NULL AUTO_INCREMENT,
    sid int NOT NULL,
    cid int NOT NULL,
    score int DEFAULT 0,
    PRIMARY KEY(mid),
    FOREIGN KEY(sid) references student(sid),
    FOREIGN KEY(cid) references course(cid)
);

insert into student values(1, 'Tom', 'male'),(2, 'Jack', 'female');
insert into course values(1, 'math');
insert into mark values(1, 1, 1, 50),(2, 2, 1, 90);