6.建立一個名為 VW_DEPT_SUM 的檢視，統計部門名字，人數，最小工資，
­­最大工資，平均工資...
create or replace view
VW_DEPT_SUM(DEPT_NAME,EMP_COUNT,MINSAL,MAXSAL,AVGSAL)
AS
SELECT d.dname,count(distinct e.empno),min(e.sal),max(e.sal),avg(e.sal)
from emp e inner join dept d on e.deptno=d.deptno
group by d.deptno;
­­7.建立一個統計大於各部門平均工資的僱員的姓名、工資、部門名、該部門平
­­均工資的檢視 VW_EMP_AVG
create or replace view VW_EMP_AVG(empname,salary ,deptname,avgsalary)
as
select
e.ename,e.sal,d.dname,(select
round(avg(sal),2)
from
emp
where
deptno=d.deptno)
from emp e inner join dept d on e.deptno=d.deptno
where e.sal>(select avg(sal) from emp);
select * from vw_emp_avg;
/*若要建立一個統計大於本人所在部門平均工資的僱員的姓名、工資、部門名、
該部門平均工資的檢視 VW_EMP_AVG01，
語句如下：*/
create or replace view VW_EMP_AVG01(empname,salary ,deptname,avgsalary)
as
select
e.ename,e.sal,d.dname,(select
round(avg(sal),2)
from
emp
where
deptno=e.deptno)
from emp e inner join dept d on e.deptno=d.deptno
where e.sal>(select avg(sal) from emp where deptno=e.deptno);
­­select * from vw_emp_avg01;