mysql 建表 插入数据 添加删除主外键

-- CREATE DATABASE school;-- use school;-- CREATE TABLE student1-- (--  id  INT UNIQUE,--  sno INT PRIMARY KEY,--  sname CHAR(10),--  ssex CHAR(2),--  sdept char(20),-- sprovince CHAR(10),-- scity CHAR(9),-- sstreet CHAR(9),-- sbirthday date DEFAULT '2010-01-01'-- );-- USE school;-- INSERT INTO student1 VALUES(2,2,'李丽','女','数学系','江苏','苏州','长桥','1997-07-18');-- INSERT INTO student1 VALUES(4,4,'张天宇','男','计算机系','上海','上海','仁义','1991-07-07');-- INSERT INTO student1 VALUES(5,5,'李大奎','男','计算机系','浙江','杭州','东营','1996-02-08');-- INSERT INTO student1 VALUES(6,6,'张思源','男','数学系','广东','深圳','华强','1989-02-06');-- INSERT INTO student1 VALUES(7,7,'tony','男','中文','浙江','杭州','东营','1996-05-29');-- INSERT INTO student1 (id,sno,sname,ssex,sdept)VALUES(9,9,'nicy','女','中文');-- INSERT INTO student1 VALUES(10,9,'李彤','女','数学系','山东','青岛','人民','1993-01-01');-- CREATE TABLE course-- (-- cno int auto_increment PRIMARY KEY,-- cname  CHAR(9),-- cpno INT,-- ccridit INT-- );-- --添加主外键 -- -- ALTER table course-- add CONSTRAINT cno_sno FOREIGN KEY (cno) REFERENCES student1(sno);-- -- 删除主外键-- ALTER table course -- DROP FOREIGN KEY cno_sno;-- INSERT INto course (cname,cpno,ccridit) VALUES('java',2,3);-- INSERT INto course (cname,cpno,ccridit) VALUES('c++',4,2);-- INSERT INto course (cname,ccridit) VALUES('数学',5);-- INSERT INto course (cname,cpno,ccridit) VALUES('c',3,3);-- INSERT INto course (cname,ccridit) VALUES('英语',5);-- INSERT INto course (cname,cpno,ccridit) VALUES('数据结构',3,3);