PL/SQL 视图

关于视图
1、什么是视图
视图实际上是一条查询语句，是数据的显示方式
2、视图的作用
安全
方便
一致性
例子1：
create or replace view myview
as
select * from abc;

 

例子2：设定检测添加数据
create or replace view myview
as
select * from abc where C>=100
with check option
/

 

例子3：两表合并查询
create or replace view v_d
as
select e.eid,e.ename,e.sex,d.name from e,d where

e.id=d.id;

 

例子4：with read only只能读
create or replace view v_read
as
select eid,ename from emp
with read only;

查询 desc dba_views
     desc all_views
     desc user_views

select text from user_views where view_name='v_read';