一.what(什么是视图?)
二.why(为什么要用视图?视图的优点)
CREATE [OR REPLACE] [FORCE|NOFORCE] VIEW view_name [(alias[, alias]...)] AS subquery [WITH CHECK OPTION [CONSTRAINT constraint]] [WITH READ ONLY]
OR REPLACE :若所创建的试图已经存在,ORACLE自动重建该视图; FORCE :不管基表是否存在ORACLE都会自动创建该视图; NOFORCE :只有基表都存在ORACLE才会创建该视图: alias :为视图产生的列定义的别名; subquery :一条完整的SELECT语句,可以在该语句中定义别名; WITH CHECK OPTION :插入或修改的数据行必须满足视图定义的约束; WITH READ ONLY :该视图上不能进行任何DML操作。
CREATE OR REPLACE VIEW dept_sum_vw (name,minsal,maxsal,avgsal) AS SELECT d.dname,min(e.sal),max(e.sal),avg(e.sal) FROM emp e,dept d WHERE e.deptno=d.deptno GROUP BY d.dname;
--给用户授权创建视图 -- grant create all view to zdgshr; 所有数据库都能创建视图的用户 grant create view to zdgshr; --创建简单视图 create view temp as select * from zd_member_basic_info; --测试 select * from temp where rownum=1; --创建简单视图:只读 create or replace view temp1 as select id,job_number,name,dept_id from zd_member_basic_info with read only; --测试 insert into temp1(id,job_number,name,dept_id) values(1,0,‘张三‘,1300);
视图的删除:
四、视图分为简单视图和复杂视图。
简单视图只从单表里获取数据;复杂视图从多表里获取数据。
简单视图不包含函数和数据组;复杂视图包含函数和数据组。
简单视图可以实现DML操作;复杂视图不可以。
create or replace view temp1 as select distinct name,job_number,dept_id from zd_member_basic_info with read only; delete from zd_member_basic_info where name=‘而过‘;
create or replace view temp as select * from zd_member_basic_info order by name;
原文:http://www.cnblogs.com/adolphyang/p/5004878.html