Oracle表连接与子查询

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　　--1、求部门中哪些人的薪水最高

select ename,sal from emp
join (select max(sal) max_sal,deptno from emp group by deptno) t
on (emp.sal = t.max_sal and emp.deptno=t.deptno);
　　
--2、求部门平均薪水的等级

select deptno,avg_sal,grade from
(select deptno,avg(sal) avg_sal from emp group by deptno) t
join salgrade s on (t.avg_sal between s.losal and s.hisal);
　　
--3、求部门平均的薪水等级

select deptno, avg(grade) from
(select deptno,ename,grade from emp join salgrade s on (emp.sal between s.losal and s.hisal)) t
group by deptno;
　　
　　--4、雇员中有哪些人是经理人

select ename from emp where empno in (select mgr from emp);
　　
　　--5、不准用组函数，求薪水的最高值

select distinct sal from emp where sal not in
(select distinct e1.sal from emp e1 join emp e2 on (e1.sal < e2.sal))
　　
--6、求平均薪水最高的部门的部门编号

㈠
select deptno,avg_sal
from (select avg(sal) avg_sal,deptno from emp group by deptno)
where avg_sal =
(select max(avg_sal)
from (select avg(sal) avg_sal,deptno from emp group by deptno)
)
㈡
select deptno,avg_sal
from (select avg(sal) avg_sal,deptno from emp group by deptno)
where avg_sal =
(select max(avg(sal)) from emp group by deptno)
　　
--7、求平均薪水最高的部门的部门名称

select dname from dept where deptno =
(
select deptno from
(select avg(sal)avg_sal,deptno from emp group by deptno)
where avg_sal =
(select max(avg_sal) from
(select avg(sal) avg_sal,deptno from emp group by deptno)
)
)
　　
　　--8、求平均薪水最高的等级最低的部门的部门名称

select dname,t1.deptno,grade,avg_sal from
(
select deptno,grade,avg_sal from
(select deptno, avg(sal) avg_sal from emp group by deptno) t
join salgrade s on (t.avg_sal between s.losal and s.hisal)
) t1
join dept on (t1.deptno = dept.deptno)
where t1.grade =
(
select min(grade) from
(
select deptno,grade,avg_sal from
(select deptno, avg(sal) avg_sal from emp group by deptno) t
join salgrade s on (t.avg_sal between s.losal and s.hisal)
)
)
　　
--9、求部门经理人中平均薪水最低的部门名称

暂无代码
　　
--10、求比普通员工的最高薪水还要高的经理人名称

select ename from emp
where empno in (select distinct mgr from emp where mgr is not null)
and sal >
(
select max(sal)from emp where empno not in
(select distinct mgr from emp where mgr is not null)
)