数据库开发基础-Oracle-SQL基础-007

练习上节[006]学习的SQL

--练习
--1.查看与CLARK相同职位的员工

select * from emp where job = (select job from emp where ename = 'CLARK');

--2.查看低于公司平均工资的员工

select * from emp where sal < (select avg(sal) from emp);

--3.查看与ALLEN同部门的员工

select *
  from emp
 where deptno = (select deptno from emp where ename = 'ALLEN');

--4.查看平均工资低于20号部门平均工资的部门平均工资

select deptno, avg(sal)
  from emp
 group by deptno
having avg(sal) < (select avg(sal) from emp where deptno = 20);

--5.查看低于自己所在部门平均工资的员工

select e.*
  from emp e, (select deptno, avg(sal) avg_sal from emp group by deptno) s
 where e.deptno = s.deptno
   and e.sal < s.avg_sal

--6.查看公司工资排名的第1-5名员工

select *
  from (select rownum rn, s.*
          from (select ename, sal from emp order by sal desc) s
         where rownum <= 5);


--7.查看CLERK职位的人数和其他职位的总人数各多少？

select decode(job, 'CLERK', 'CLERK', 'OTHER'), count(*)
  from emp
 group by decode(job, 'CLERK', 'CLERK', 'OTHER');


--8.查看每个职位的工资排名

select ename,
       sal,
       job,
       row_number() over(partition by job order by sal desc)
  from emp;

--9.查看每个职位的工资排名，若工资一致，排名一致

select ename, sal, job, rank() over(partition by job order by sal desc)
  from emp;
  
--10.查看每个职位的工资排名，若工资一致，排名一致，不跳名次

select ename,
       sal,
       job,
       dense_rank() over(partition by job order by sal desc)

  from emp;

--11.分别查看：同部门同职位，[同职位]，以及所有员工的工资总和

/*select deptno, job, sum(sal)
  from emp
 group by rollup(deptno, job)
 order by deptno, job;*/

select deptno, job, sum(sal)
  from emp
 group by rollup(job,deptno)
 order by deptno, job;

--12.分别查看：同部门同职位，同职位，同部门以及所有员工的工资总和

select deptno, job, sum(sal)
  from emp
 group by cube(deptno, job)
 order by deptno, job;

--13.分别查看同部门同职位和同职位的员工的工资总和

select deptno, job, sum(sal)
  from emp
 group by grouping sets((deptno, job), job)
 order by deptno, job;