视图

//创建视图

create view empno(ename,job,hiredate)
as
select ename,job,hiredate from emp;

create view empno as select * from emp;

//删除视图

drop view empno;

//创建视图并且能够替换掉视图

create or replace 视图名称 as 子查询

//更新视图

with check option:不能更新视图的创建条件

create view empno(ename,job,hiredate)
as
select ename,job,hiredate from emp

with check option;

//视图只读

with read only：创建的视图只读

create view empno(ename,job,hiredate)
as
select ename,job,hiredate from emp

with read only;