SQL基础学习笔记（四）—视图

标签：

create view empview
as 
select employee_id id, last_name name, salary sal
from employees
where department_id = 80

update empview
set salary = 10000
where employee_id = 179

（于此同时，employees表中的工号179的人的salary也是10000）

delete from empview
 where employee_id = 176;

create view empview2
as
select employee_id id , last_name name, salary sal ,department_name 
from employees e, departments d
where e.department_id = d.department_id

修改视图create or replace

create or replace view empview2
as
select employee_id id , last_name name
from employees e, departments d
where e.department_id = d.department_id

这样就会将原来的视图覆盖

create or replace view empview2
as
select employee_id id , last_name name
from employees e, departments d
where e.department_id = d.department_id
with read only

这个视图只能读，不能改

create or replace view empview3
as
select department_name dept_name,avg(salary) avg_sal
from employees e , departments d
where e.department_id = d.department_id
group by department_name

 drop view empview3;

select rownum, employee_id , last_name , salary
from   (
       select employee_id , last_name , salary
       from employees
       order by salary desc
       )
where rownum <= 10

查询工资排名40-50名之间

select rn , employee_id , last_name , salary
from (
     select rownum, employee_id , last_name , salary
            from   (
                     select employee_id , last_name , salary
                      from employees
                      order by salary desc
                    )
     )
where rn > 40 and rn <50

SQL基础学习笔记（四）—视图

标签：

原文地址：http://blog.csdn.net/wjw0130/article/details/43532245