建立数据库
create database zhangjiaxing
自动定位到建立的数据库
use zhangjiaxing
建立数据表
students表
create table students
(
sno char(5) primary key,
sname char(20) not null unique,
ssex char(2) constraint de_ssex default '男',
sage int check (sage between 16 and 24),
sdept char(15) check (sdept in ('电子商务','计算机','数学'))
)
courses表
create table courses
(
cno char(5) primary key,
cname char(20) not null,
pre_cno char(5) references courses(cno),
credits int,
);
reports表
create table reports
(
sno char(5) references students(sno),
cno char(5) references courses(cno),
grade int check (grade>=0 and grade<=100),
constraint sno_cno primary key(sno,cno)
);
插入数据
表的关系
向students表中插入数据
/*insert into students values('s01','王建平','男',21,'电子商务')
insert into students values('s02','刘华','女',19,'电子商务')
insert into students values('s03','范林军','女',18,'计算机')
insert into students values('s04','李伟','男',19,'计算机')
insert into students values('s05','黄河','男',18,'数学')
insert into students values('s06','长江','男',20,'数学')
insert into students values('s38','张家兴','男',22,'计算机')*/
select * from students
向courses表插入数据
/*insert into courses values('c01','英语',null,4)
insert into courses values('c05','C++',null,3)
insert into courses values('c02','数据结构','c05',2)
insert into courses values('c03','数据库','c02',2)
insert into courses values('c04','DB_设计','c03',3)
insert into courses values('c07','操作系统','c05',3)
insert into courses values('c06','网络原理','c07',3)*/
select * from courses
注意要根据表的关系来定插入表的顺序
向reports表添加数据(使用企业管理器管理表格数据)
修改表的数据
将students表中sno=s01的同学的sage改为22
update students set sage=22 where sno='s01'
将students表中sno=s03的同学的ssex改为男,sage改为17
update students set ssex='男',sage=17 where sno='s03'
将students表中所有人的sage+1
update students set sage=1+sage
数据库表的合并(条件合并)
select *
from students,courses,reports
where students.sno=reports.sno
and courses.cno=reports.cno