维护对象类型

1,显示对象类型的信息–user_types

select type_name,attributes,final from user_types where type_name =’PERSON_TYP9’ ;

desc person_typ9;

2,增加和删除对象类型的属性

alter type person_typ9 add attribute
age number(4) cascade;–级联
alter type person_typ9 drop attribute age cascade;

select * from employee_tab9;

3,添加和删除对象方法

alter type　PERSON_TYP9　add
member function get_name return varchar2
cascade;
create or replace type body PERSON_TYP9 as
member function get_name return varchar2
is
begin
return name;
end;
end;

修改表

–添加一列
alter table emp add age varchar2(11) ;

alter table emp add constraint –添加约束条件
age check(age<100) ;

alter table emp drop constraint age ; –删除约束条件