Oracle视图的创建、使用以及删除操作方法大全

    create or replace view 视图名称_V
    as
    查询的逻辑 （select）；
   -- with read only； 可以增加只读属性

select * from 视图名；

DROP VIEW 视图名_V;

create or replace view aa_v 
as 
select f.deptno 部门编号,f.dname 部门名称 ,count(e.empno) 部门人数 ,
avg(e.sal) 平均工资,max(e.sal) 最大工资,min(e.sal) 最小工资,sum(e.sal) 工资总和
from dept f
left join emp e
on f.deptno=e.deptno
group by f.deptno,f.dname
order by f.deptno;

select * from aa_v;

create or replace view bb_v 
as 
select empno,ename,job,mgr,deptno
from emp;

select * from bb_v;

create table emp_111 as select * from emp;

create or replace view cc_v 
as 
select empno,ename,job,mgr,deptno
from emp_111;

select * from cc_v;

update cc_v set deptno=50 where empno=7788;
commit; --提交

select * from cc_v;

select * from emp_111;

create or replace view dd_v 
as 
select empno,ename,job,mgr,deptno
from emp_111
with read only;  --加上只读属性

select * from dd_v;

update cc_v set deptno=50 where empno=7788;
commit; --提交

CREATE OR REPLACE  VIEW EMP_ENAME_V 
AS 
SELECT T.EMPNO
      ,T.ENAME
      ,T.DEPTNO
      ---函数返回的结果一定要给别名
      ,TO_CHAR(T.HIREDATE,'YYYY') as rz_year
FROM EMP T; --基表

select * from EMP_ENAME_V; --查询视图就是查询视图中封装的sql逻辑的内容;

SELECT * FROM EMP_ENAME_V TWHERE T.EMPNO = 7369;

CREATE OR REPLACE VIEW EMP_DEPT_V 
AS 
SELECT T.EMPNO
      ,T.ENAME
      ,T2.DNAME
FROM EMP_ENAME_V T
INNER JOIN DEPT T2
        ON T.DEPTNO = T2.DEPTNO;

SELECT * FROM EMP_DEPT_V;

DROP VIEW EMP_DEPT_V;

create or replace view hh_v
as
with table1 as(select * from emp where deptno=10),
     table2 as(select * from emp where deptno=20),
     table3 as(select* from dept)
     
     select e.*,f.dname,f.loc from table1 e
     inner join table3 f
     on e.deptno = f.deptno;

select * from hh_v;