维勒斯.txt

关于oracle和sql的书籍和ppt教程,非常好,本人珍藏品

1.

创建商品表 
create table merchandise (id int,name varchar2(10),sort varchar2(10)，price number(5,2));
创建种类表
create table class (id int primary key,sort varchar2(10));

对种类表设置非空和唯一性
alter table class modify sort not null;
alter table class add unique(sort);
种类表已完善

添加商品表约束：主键，外键，检查
alter table merchandise add constraint pk primary key (id,name);
alter table merchandise add constraint fk foreign key (sort) references class (sort);
alter table merchandise add constraint ck check (price>0);
商品表基本完善


商品表仍不符合第二范式规范，因为种类价格不能由id和name完全确定。如新加入商品，可能出现同一商品几种种类或价格的问题。欲完善之，还应建立价格表和种类清单表。

*******************************************************

2.

SQL> insert into class values (1,'food');
SQL> insert into class values (2,'commodity');
SQL> insert into class values (3,'medicine');
SQL> insert into merchandise values (1,'steak','food',7.00);
SQL> insert into merchandise values (2,'soap','commodity',0.50);
SQL> insert into merchandise values (3,'aspirin','medicine',15.50);
SQL> insert into merchandise values (3,'aaa','medicine',0.10);
SQL> delete from merchandise where price=0.10;
SQL> update merchandise set name='steak' where id=2;
SQL> select * from merchandise;

                                     ID NAME       SORT         PRICE
--------------------------------------- ---------- ---------- -------
                                      1 steak      food          7.00
                                      2 steak      commodity     0.50
                                      3 aspirin    medicine     15.50


---------------------
出现了增异常和改异常