练习

-- 1、查询emp中最高薪水人的名字

select max(SAL) from EMP;

select ENAME from EMP where

SAL=(select max(SAL) from EMP);

--

-- 2、查询每个部门中的最高薪水人的名字和所在的部门编号

select max(SAL),DEPTNO from EMP

GROUP BY DEPTNO;

select t1.ename,t1.deptno from EMP t1

INNER JOIN(select max(SAL) max_sal,DEPTNO from EMP group by deptno)t2

on t1.deptno=t2.deptno and sal=t2.max_sal

-- 3、查询薪水在平均薪水之上的雇员的名字

select AVG(SAL) from EMP;

select ENAME from EMP where SAL>(select AVG(SAL) from EMP);

-- 4、查询雇员的名字和所在部门的名字

select t1.ENAME,t2.DNAME from EMP t1,DEPT t2

where t1.deptno=t2.deptno;

-- 5、查询薪水在在本部门平均薪水之上的雇员的名字

select t1.ENAME,t1.deptno from EMP t1

INNER JOIN (select avg(sal) avg_sal,deptno from EMP GROUP BY deptno)t2

on t1.deptno=t2.deptno and sal>t2.avg_sal;

-- 6、查询每个员工的薪水的等级,员工的姓名

select * from EMP;

select * from SALGRADE;

select t1.ename,t2.grade from EMP t1,SALGRADE t2

where t1.sal BETWEEN t2.LOSAL and t2.HISAL;

-- 7、查询每个部门的平均薪水的等级,部门的编号

select avg(sal),deptno from EMP GROUP BY deptno;

select t1.grade,t2.deptno from SALGRADE t1,(select avg(sal) avg_sal,deptno from EMP GROUP BY deptno) t2

where t2.avg_sal BETWEEN t1.losal and t1.hisal;

-- 8、查询雇员的名字，所在部门的名字，工资的等级

select t1.ENAME,t2.DNAME,t3.grade from EMP t1,DEPT t2,SALGRADE t3

where t1.deptno=t2.deptno

and t1.sal BETWEEN t3.LOSAL and t3.HISAL;

-- 9、查询雇员的名字和其经理的名字

select t1.ENAME,t2.JOB from EMP t1,EMP t2

where t1.EMPNO=t2.MGR;

-- 10、查询雇员中是经理人的名字

select distinct mgr from EMP;

select ename from EMP where empno in(select distinct mgr from EMP)

-- 14、查询薪水最高的前5名雇员编号，名称，薪水

select empno,ename,sal from EMP

order by sal desc

limit 5;

-- 15、查询薪水最高的第6名到第10名雇员编号，名称，薪水

select empno,ename,sal from EMP

order by sal desc

limit 5,5;