course 系统

 create database class;   
use class;      
create table course(     
cname varchar(20)  primarykey,
cno int,
cteacher varchar(20));
insert into course values("math",1,"lisa"),("eng",2,"jane"),("chin",3,"lin"),
update course set cno="4" where cname="chin"; 

select * from course where cname="math";

select * from course where cno between 1and 3;

delete from course where cname="chin";