数据库SQL查询表的建立教程
建学生表
create table student
(snochar(9) primary key,
snamechar(20) unique,
ssex char(2),
sage smallint,
sdept char(20)
);
create table course
(cnochar(4) primary key,
cnamechar(40) no null,
cpnochar(4),
ccreditsmallint,
foreignkey (cpno) references course(cno)
);
create table sc
(snochar(9),
cnochar(4),
gradesmallint,
primarykey(sno, cno),
foreignkey(sno) references student(sno),
foreignkey(cno) references course(cno)
);
insert
into student(sno,sname,ssex,sage,sdept)
values('201215121','李勇','男',20,'cs')；
insert
into student (sno,sname,ssex,sage,sdept)
values ('201215122','刘晨','女',19,'cs');
insert
into student (sno,sname,ssex,sage,sdept)
values ('201215123','王敏','女',18,'ma');
insert
into student (sno,sname,ssex,sage,sdept)
values ('201215125','张立','男',19,'is');
insert
into course(cno,cname,cpno,ccredit)
values(‘2’,’数学’,’null’,’2’);
insert
into course(cno,cname,cpno,ccredit)
values(‘6’,’数据处理’,’null’,’2’);
insert
into course(cno,cname,cpno,ccredit)
values(‘4’,’操作’,’6’,’3’);
insert
into course (cno,cname,cpno,ccredit)
values('7','pscal语言','6','4');
insert
into course (cno,cname,cpno,ccredit)
values('5','数据结构','7','4');
insert
into course (cno,cname,cpno,ccredit)
values('1','','5','4');
insert
into course (cno,cname,cpno,ccredit)
values('3','信息系统','1','4');
insert
into sc(sno,cno,grade)
values(‘200215121’,’1’,’92’);
insert
into sc (sno,cno,grade)
values('200215121','2','85');
insert
into sc (sno,cno,grade)
values('200215121','3','88');
insert
into sc (sno,cno,grade)
values('200215122','2','90');
insert
into sc (sno,cno,grade)
values('200215122','3','80');