-- 初始化的SQL脚本
create table dept(
DEPTNO int(2),
DNAME varchar(14),
LOC varchar(13)
);
INSERT INTO dept values(10, 'ACCOUNTING', 'NEW YORK');
INSERT INTO dept values(20, 'RESEARCH', 'DALLAS');
INSERT INTO dept values(30, 'SALES', 'CHICAGO');
INSERT INTO dept values(40, 'OPERATIONS', 'BOSTON');
create table emp(
EMPNO int(4),
ENAME varchar(10),
JOB varchar(9),
MGR int(4),
HIREDATE date,
SAL double(7,2),
COMM double(7,2),
DEPTNO int(2)
);
INSERT INTO emp values(7369,'SMITH','CLERK',7902,'1980-12-17',800,NULL,20);
INSERT INTO emp values(7499,'ALLEN','SALESMAN',7698,'1981-02-20',1600,300,30);
INSERT INTO emp values(7521,'WARD','SALESMAN',7698,'1981-02-22',1250,500,30);
INSERT INTO emp values(7566,'JONES','MANAGER',7839,'1981-04-02',2975,NULL,20);
INSERT INTO emp values(7654,'MARTIN','SALESMAN',7698,'1981-09-28',1250,1400,30);
INSERT INTO emp values(7698,'BLAKE','MANAGER',7839,'1981-05-01',2850,NULL,30);
INSERT INTO emp values(7782,'CLARK','MANAGER',7839,'1981-06-09',2450,NULL,10);
INSERT INTO emp values(7788,'SCOTT','ANALYST',7566,'1987-04-19',3000,NULL,20);
INSERT INTO emp values(7839,'KING','PRESIDENT',NULL,'1981-11-17',5000,NULL,10);
INSERT INTO emp values(7844,'TURNER','SALESMAN',7698,'1981-09-08',1500,0,30);
INSERT INTO emp values(7876,'ADAMS','CLERK',7788,'1987-05-23',1100,NULL,20);
INSERT INTO emp values(7900,'JAMES','CLERK',7698,'1981-12-03',950,NULL,30);
INSERT INTO emp values(7902,'FORD','ANALYST',7566,'1981-12-03',3000,NULL,20);
INSERT INTO emp values(7934,'MILLER','CLERK',7782,'1982-01-23',1300,NULL,10);
create table salgrade(
GRADE int(11),
HISAL int(11),
LOSAL int(11)
);
INSERT INTO SALGRADE VALUES (1,1200,700);
INSERT INTO SALGRADE VALUES (2,1400,1201);
INSERT INTO SALGRADE VALUES (3,2000,1401);
INSERT INTO SALGRADE VALUES (4,3000,2001);
INSERT INTO SALGRADE VALUES (5,9999,3001);
-- 取得每个部门最高薪水的人员名称
SELECT
e.ename
FROM
emp e
JOIN
(SELECT
deptno, MAX(sal) AS maxsal
FROM
emp
GROUP BY deptno) t ON e.deptno = t.deptno
WHERE
t.maxsal = e.sal;
-- 哪些人的薪水在部门平均薪水之上
SELECT
e.ename, e.sal, e.deptno
FROM
emp e
JOIN
(SELECT
deptno, AVG(sal) AS avgsal
FROM
emp
GROUP BY deptno) t ON e.deptno = t.deptno
WHERE
e.sal > t.avgsal;
-- 取得部门中（所有人的）平均薪水等级
SELECT
t.deptno, t.avgsal, s.grade
FROM
salgrade s
JOIN
(SELECT
deptno, AVG(sal) avgsal
FROM
emp
GROUP BY deptno) t ON t.avgsal BETWEEN s.losal AND s.hisal;
-- 不用max函数，取得最高薪水
SELECT
sal
FROM
emp
ORDER BY sal DESC
LIMIT 0 , 1;
-- 取得平均薪水最高的部门的部门编号
SELECT
t.deptno, t.avgsal
FROM
(SELECT
deptno, AVG(sal) avgsal
FROM
emp
GROUP BY deptno) AS t
HAVING MAX(avgsal);
-- 取得平均薪水最高的部门的部门名称
SELECT
DNAME
FROM
dept d
JOIN
(SELECT
t.DEPTNO, MAX(avgsal)
FROM
(SELECT
DEPTNO, AVG(sal) AS avgsal
FROM
emp
GROUP BY DEPTNO) t) s ON d.DEPTNO = s.DEPTNO
;
-- 求平均薪水的等级最低的部门的部门名称
SELECT
DNAME
FROM
dept dd
JOIN
(SELECT
GRADE, d.DEPTNO AS DEPTNO
FROM
salgrade s
JOIN (SELECT
DEPTNO, AVG(sal) avgsal
FROM
emp
GROUP BY DEPTNO
ORDER BY avgsal ASC
LIMIT 0 , 1) d ON avgsal BETWEEN LOSAL AND HISAL) ff ON dd.DEPTNO = ff.DEPTNO;
