子查询和表连接
①.查询挣钱最多的人的名字
SELECT ename,sal FROM emp
WHERE sal=(SELECT MAX(sal) FROM emp);
②.查询有哪些人的工资位于所有人的平均工资之上
SELECT ename,sal FROM emp
WHERE sal > (SELECT AVG(sal) FROM emp);
③.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;
④.求出员工的名字和他的经理人姓名
SELECT e1.ename, e2.ename FROM
emp e1 JOIN emp e2
ON e1.mgr = e2.empno;
⑤.查询出每个人的薪水等级
SELECT ename,grade FROM emp e JOIN salgrade s
ON (e.sal BETWEEN s.losal AND s.hisal);
⑥查询出每个人的部门名称和薪水等级
SELECT ename,dname,grade FROM
emp e JOIN dept d ON (e.deptno =d.deptno)
JOIN salgrade s ON (e.sal BETWEEN s.losal AND s.hisal)
⑦(左外连接) 查询出雇员的名字和他经理人的名字
SELECT e1.ename, e2.ename FROM
emp e1 LEFT JOIN emp e2
ON e1.mgr = e2.empno;
⑧(右外连接) 查询出所有雇员的部门名称
SELECT ename ,dname FROM
emp e RIGHT JOIN dept d
ON e.deptno = d.deptno;
⑨(全外连接) 查询出所有雇员的部门名称
SELECT ename ,dname FROM
emp e FULL JOIN dept d
ON e.deptno = d.deptno;
⑩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;
--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;
--求雇员中哪些人是经理人
SELECT ename FROM emp
WHERE empno in(SELECT DISTINCT mgr FROM emp);
--不准用组函数,求薪水的最高值
SELECT sal FROM emp WHERE sal NOT IN
(SELECT DISTINCT e1.sal FROM emp e1 JOIN emp e2
ON e1.sal< e2.sal);
--平均薪水最高的部门的部门编号
SELECT deptno ,avg_sal FROM
( SELECT deptno, AVG(sal) avg_sal FROM emp GROUP BY deptno);
WHERE avg_sal =
(SELECT MAX(avg_sal) FROM
( SELECT deptno, AVG(sal) avg_sal FROM emp GROUP BY deptno));
--平均薪水最高的部门的部门名称
SELECT dname FROM dept WHERE deptno =
(SELECT deptno FROM
( SELECT deptno, AVG(sal) avg_sal FROM emp GROUP BY deptno)
WHERE avg_sal =
(SELECT MAX(avg_sal) FROM
( SELECT deptno, AVG(sal) avg_sal FROM emp GROUP BY deptno)
)
);
--求平均薪水的等级最低的部门的部门名称
SELECT dept.dname,t1.deptno,grade,avg_sal FROM
(
SELECT deptno,grade,avg_sal FROM
(SELECT AVG(sal) avg_sal, deptno 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 AVG(sal) avg_sal, deptno FROM emp GROUP BY deptno) t JOIN salgrade s
ON t.avg_sal BETWEEN s.losal AND s.hisal))
--求部门经理人平均薪水最低的部门名称
--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))
--求薪水最高的前5名雇员
SELECT ename,sal
FROM (
SELECT ename,sal FROM emp ORDER BY sal DESC
)
WHERE ROWNUM <=5;
--求薪水最高的第6到第10名雇员
SELECT ename,sal FROM(
SELECT ename,sal, ROWNUM r FROM(
SELECT ename,sal FROM emp ORDER BY sal DESC)
)
