【数据库】基本操作

create table customer

(

  cno,int,PRIMARY KEY IDENTITY(1,1), 

   cna,vachar(10),not null,

   adr,vachar(100),not null;

   );

create table cp
(
  cno,int,FOREIGN KEY REFERENCES customer(cno),
  pno,int,REFERENCES paper(pno),//设置外键
  PRIMARY KEY(cno,pno),//两个主键
  num int DEFAULT ((1)), //缺省值，即默认值
  );

创建视图
Create view C_P_N as
Select customer.cno,customer.cna ,paper.pna,paper.pno ,cp.num from cp,paper,customer;
修改视图
alter view C_P_N as
Select customer.cno,customer.cna ,paper.pna,paper.pno ,cp.num, paper.ppr from cp,paper,customer;
查询视图
select * from C_P_N
where pna = ‘人民日报‘;
修改视图数据
UPDATE C_P_N SET num =10 WHERE cna =‘李涛‘ and pna=‘人民日报‘ and pno = 1 and num=2 ;
删除视图
DROP VIEW C_P_N