--1.列出至少有三个员工的所有部门和部门信息。
SELECT D.DEPTNO, D.DNAME, D.LOC, T.COUNTS
FROM DEPT D, (SELECT DEPTNO, COUNT(*) COUNTS FROM EMP GROUP BY DEPTNO) T
WHERE D.DEPTNO = T.DEPTNO
AND T.COUNTS >= 3;
--2.列出受雇日期早于直接上级的所有员工的编号，姓名，部门名称
SELECT E.EMPNO, E.ENAME, D.DNAME
FROM EMP E, EMP M, DEPT D
WHERE E.MGR = M.EMPNO
AND E.HIREDATE < M.HIREDATE
AND E.DEPTNO = D.DEPTNO;
--3.列出职位为“CLERK”的员工姓名和其所在部门名称，部门人数：
SELECT e.ename,d.dname,t.counts
FROM emp e, dept d,
(SELECT deptno de, COUNT(*) counts FROM emp GROUP BY deptno )t
WHERE e.deptno = d.deptno AND e.deptno = t.de AND e.job = 'CLERK';
--4.列出和“SCOTT”从事相同工作的所有员工及部门名称：
SELECT E.*, D.DNAME
FROM EMP E, DEPT D
WHERE E.DEPTNO = D.DEPTNO
AND E.JOB = (SELECT JOB FROM EMP WHERE ENAME = 'SCOTT');
--5.列出每个部门工作的员工数量、平均工资和平均服务期限（单位为年）
SELECT DEPTNO "部门编号",
COUNT(EMPNO) "人数",
ROUND(AVG(SAL)) "平均薪资",
ROUND(AVG(MONTHS_BETWEEN(SYSDATE, HIREDATE))/12) "服务年限"
FROM EMP
GROUP BY DEPTNO;
--6、列出各个部门的MANAGER 的最低薪金：
SELECT deptno, MIN(sal) FROM emp WHERE job = 'MANAGER' GROUP BY deptno;
--7、给任职日期超过10年的人加薪10%；
SELECT E.*, E.SAL * 1.1
FROM EMP E
WHERE (MONTHS_BETWEEN(SYSDATE, HIREDATE)) / 12 > 10;