搭建一个简易的成绩管理系统的数据库
题目描述
我的实现：

CREATE DATABASE gradesystem;

USE gradesystem;

CREATE TABLE student
(
sid  INT(12) PRIMARY KEY auto_increment,
sname VARCHAR(20),
gender VARCHAR(12)
);


CREATE TABLE course
(
cid INT(12) PRIMARY KEY auto_increment,
cname VARCHAR(20)
);

CREATE TABLE mark
(
mid INT(12) PRIMARY KEY auto_increment,
sid INT(12),
cid INT(12),
score INT(12),
FOREIGN KEY(sid) references student(sid),
FOREIGN KEY(cid) references course(cid)
);



insert into student (sid, sname,gender)  values(1, 'Tom', 'male'), (2, 'Jack','male'), (3,'Rose','female');

insert into course (cid, cname)  values(1, 'math'), (2, 'physics'), (3,'chemistry');

insert into mark (mid,sid,cid, score)  values(1, 1,1,80),(2,2,1,85),(3,3,1,90),(4,1,2,60),(5,2,2,90),(6,3,2,75),(7,1,3,95),(8,2,3,75),(9,3,3,85);

另一个代码实例：

CREATE DATABASE mysql_shiyan;

use mysql_shiyan;

CREATE TABLE department
(
  dpt_name   CHAR(20) NOT NULL,
  people_num INT(10) DEFAULT '10',
  CONSTRAINT dpt_pk PRIMARY KEY (dpt_name)
 );

CREATE TABLE employee
(
  id      INT(10) PRIMARY KEY,
  name    CHAR(20),
  age     INT(10),
  salary  INT(10) NOT NULL,
  phone   INT(12) NOT NULL,
  in_dpt  CHAR(20) NOT NULL,
  UNIQUE  (phone),
  CONSTRAINT emp_fk FOREIGN KEY (in_dpt) REFERENCES department(dpt_name)
 );

CREATE TABLE project
(
  proj_num   INT(10) NOT NULL,
  proj_name  CHAR(20) NOT NULL,
  start_date DATE NOT NULL,
  end_date   DATE DEFAULT '2015-04-01',
  of_dpt     CHAR(20) REFERENCES department(dpt_name),
  CONSTRAINT proj_pk PRIMARY KEY (proj_num,proj_name)
 );