数据库表的创建与管理

1、使用SQL语言定义Student表，该表的结构描述如下：

Create table Student
(  
	Sno varchar(9) primary key not null,		
	Sname varchar(20) unique not null,
	Ssex char (2) check(Ssex='男'or Ssex='女'),  
	Sage int,
	Sdept varchar(20) default('计算机科学系')
)

not null意为非空，primary意为主码，unique意为唯一，check意为检查，default意为默认。 

select * from Student        //用这个语句查看表

 

2、使用SQL语言定义Course表，该表的结构描述如下：

Create table Course
(
	Cno varchar(4) primary key not null,
	Cname varchar(40),
	Cpon varchar(4) foreign key references course(Cno),
	Credit int,
)

 referenceces一句，意为外码，即外键。此处Cpno与Course也即自身的Cno连接，题目有些奇怪！

select * from Course       //用这个语句查看表

 

3、使用SQL语言定义SC表，该表的结构描述如下：

Create table Sc 		
(
	Sno varchar(9) foreign key references Student(Sno),
	Cno varchar(4) foreign key references Course(Cno),
	Grade int check(Grade between 0 and 100),
	Primary key(Sno,Cno)
)

select * from Sc      //查看Sc表

 

4、使用INSERT语句将下面三个表中的数据插入到相应的表中

insert into Student(Sno,Sname,Ssex,Sage,Sdept) values ('200215121','李勇','男',20,'CS');
insert into Student values('200215122','刘晨','女',19,'CS');
insert into Student values('200215123','王敏','女',18,'NA');
insert into Student values('200215124','张立','男',19,'IS');

insert into Course values('1','数据库','5',4);    //特别注意数据类型，单引号
insert into Course values('2','数学',null,4);
insert into Course values('3','信息系统','1',4);
insert into Course values('4','操作系统','6',3);
insert into Course values('5','数据结构','7',4);
insert into Course values('6','数据处理',null,2);
insert into Course values('7','PASCAL语言','6',4);

insert into Sc values('200215121','1',92);
insert into Sc values('200215121','2',85);
insert into Sc values('200215121','3',88);
insert into Sc values('200215122','2',90);
insert into Sc values('200215122','3',80);
insert into Sc values('200215123','4',87);
insert into Sc values('200215123','5',92);

 

5、使用ALTER TABLE 语句修改Student表为其增加一个Birthday列，类型为DATETIME

Alter table student
Add Birthday Datetime

6、删除表Student的“Birthday”属性列

Alter table student
Drop column Birthday

 

7、在表SC中插入某个学生的选课信息，学号为“200215121”，课程号为“5”，成绩待定

insert into Sc values('200215121','5',0);

 

8、表Student将学号为“200215124”的学生的学号修改为“200215188”

update Student set Sno = '200215188' where Sno = '200215124'

 

9、修改CS系姓名为“李勇”的学生姓名为“李咏”

update Student set Sname = '李咏' where Sname = '李勇'

 

10、将选修了课程“1”的同学成绩加5分

update Sc set Grade = Grade + 5 where Cno = '1'

11、向Student表中增加一个新学生：学号是200215199，姓名是王婧婧、性别是女、系别是CS、年龄是21

insert into Student(Sno,Sname,Ssex,Sage,Sdept) values ('200215199','王婧婧','女',21,'CS');

12、表Student将学号为“200215199”的学生信息重新设置为“王丹丹、女、20，MA”

update Student set Sname = '王丹丹',Ssex = '女',Sage = '20',Sdept = 'MA' where Sname = '王婧婧'

 

 13、Student将学号为“200215199”的学生的系别重新设置NULL

update Student set Sdept = NULL where Sno = '200215199'

 

14、删除数据表student中无系别的学生记录

delete from Student where Sdept is null

 

15、利用SQL语句建立如下所示的表customer

Create table customer
(
	customid varchar(17) primary key,
	name varchar(10) unique,
	sex varchar(2) check(sex='男'or sex='女'),
	age int check(age between 18 and 45),
	bill Dec(10,2),
	address varchar(50),
	memo varchar(100)，
)