MYSQL 练习题

表的创建

table DEPT

/*
 Navicat Premium Data Transfer

 Source Server         : localhost
 Source Server Type    : MySQL
 Source Server Version : 80020
 Source Host           : localhost:3306
 Source Schema         : bjpowernode

 Target Server Type    : MySQL
 Target Server Version : 80020
 File Encoding         : 65001

 Date: 06/01/2021 12:13:18
*/

SET NAMES utf8mb4;
SET FOREIGN_KEY_CHECKS = 0;

-- ----------------------------
-- Table structure for dept
-- ----------------------------
DROP TABLE IF EXISTS `dept`;
CREATE TABLE `dept`  (
  `DEPTNO` int(0) NOT NULL,
  `DNAME` varchar(14) CHARACTER SET utf8 COLLATE utf8_general_ci NULL DEFAULT NULL,
  `LOC` varchar(13) CHARACTER SET utf8 COLLATE utf8_general_ci NULL DEFAULT NULL,
  PRIMARY KEY (`DEPTNO`) USING BTREE
) ENGINE = InnoDB CHARACTER SET = utf8 COLLATE = utf8_general_ci ROW_FORMAT = Dynamic;

-- ----------------------------
-- Records of dept
-- ----------------------------
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');
INSERT INTO `dept` VALUES (50, 'renshibu', 'shanghai');

SET FOREIGN_KEY_CHECKS = 1;

table EMP

/*
 Navicat Premium Data Transfer

 Source Server         : localhost
 Source Server Type    : MySQL
 Source Server Version : 80020
 Source Host           : localhost:3306
 Source Schema         : bjpowernode

 Target Server Type    : MySQL
 Target Server Version : 80020
 File Encoding         : 65001

 Date: 06/01/2021 12:14:45
*/

SET NAMES utf8mb4;
SET FOREIGN_KEY_CHECKS = 0;

-- ----------------------------
-- Table structure for emp
-- ----------------------------
DROP TABLE IF EXISTS `emp`;
CREATE TABLE `emp`  (
  `EMPNO` int(0) NOT NULL,
  `ENAME` varchar(10) CHARACTER SET utf8 COLLATE utf8_general_ci NULL DEFAULT NULL,
  `JOB` varchar(9) CHARACTER SET utf8 COLLATE utf8_general_ci NULL DEFAULT NULL,
  `MGR` int(0) NULL DEFAULT NULL,
  `HIREDATE` date NULL DEFAULT NULL,
  `SAL` double(7, 2) NULL DEFAULT NULL,
  `COMM` double(7, 2) NULL DEFAULT NULL,
  `DEPTNO` int(0) NULL DEFAULT NULL,
  PRIMARY KEY (`EMPNO`) USING BTREE
) ENGINE = InnoDB CHARACTER SET = utf8 COLLATE = utf8_general_ci ROW_FORMAT = Dynamic;

-- ----------------------------
-- Records of emp
-- ----------------------------
INSERT INTO `emp` VALUES (7369, 'SMITH', 'CLERK', 7902, '1980-12-17', 800.00, NULL, 20);
INSERT INTO `emp` VALUES (7499, 'ALLEN', 'SALESMAN', 7698, '1981-02-20', 1600.00, 300.00, 30);
INSERT INTO `emp` VALUES (7521, 'WARD', 'SALESMAN', 7698, '1981-02-22', 1250.00, 500.00, 30);
INSERT INTO `emp` VALUES (7566, 'JONES', 'MANAGER', 7839, '1981-04-02', 2975.00, NULL, 20);
INSERT INTO `emp` VALUES (7654, 'MARTIN', 'SALESMAN', 7698, '1981-09-28', 1250.00, 1400.00, 30);
INSERT INTO `emp` VALUES (7698, 'BLAKE', 'MANAGER', 7839, '1981-05-01', 2850.00, NULL, 30);
INSERT INTO `emp` VALUES (7782, 'CLARK', 'MANAGER', 7839, '1981-06-09', 2450.00, NULL, 10);
INSERT INTO `emp` VALUES (7788, 'SCOTT', 'ANALYST', 7566, '1987-04-19', 3000.00, NULL, 20);
INSERT INTO `emp` VALUES (7839, 'KING', 'PRESIDENT', NULL, '1981-11-17', 5000.00, NULL, 10);
INSERT INTO `emp` VALUES (7844, 'TURNER', 'SALESMAN', 7698, '1981-09-08', 1500.00, 0.00, 30);
INSERT INTO `emp` VALUES (7876, 'ADAMS', 'CLERK', 7788, '1987-05-23', 1100.00, NULL, 20);
INSERT INTO `emp` VALUES (7900, 'JAMES', 'CLERK', 7698, '1981-12-03', 950.00, NULL, 30);
INSERT INTO `emp` VALUES (7902, 'FORD', 'ANALYST', 7566, '1981-12-03', 3000.00, NULL, 20);
INSERT INTO `emp` VALUES (7934, 'MILLER', 'CLERK', 7782, '1982-01-23', 1300.00, NULL, 10);

SET FOREIGN_KEY_CHECKS = 1;

table salgrade

/*
 Navicat Premium Data Transfer

 Source Server         : localhost
 Source Server Type    : MySQL
 Source Server Version : 80020
 Source Host           : localhost:3306
 Source Schema         : bjpowernode

 Target Server Type    : MySQL
 Target Server Version : 80020
 File Encoding         : 65001

 Date: 06/01/2021 12:14:51
*/

SET NAMES utf8mb4;
SET FOREIGN_KEY_CHECKS = 0;

-- ----------------------------
-- Table structure for salgrade
-- ----------------------------
DROP TABLE IF EXISTS `salgrade`;
CREATE TABLE `salgrade`  (
  `GRADE` int(0) NULL DEFAULT NULL,
  `LOSAL` int(0) NULL DEFAULT NULL,
  `HISAL` int(0) NULL DEFAULT NULL
) ENGINE = InnoDB CHARACTER SET = utf8 COLLATE = utf8_general_ci ROW_FORMAT = Dynamic;

-- ----------------------------
-- Records of salgrade
-- ----------------------------
INSERT INTO `salgrade` VALUES (1, 700, 1200);
INSERT INTO `salgrade` VALUES (2, 1201, 1400);
INSERT INTO `salgrade` VALUES (3, 1401, 2000);
INSERT INTO `salgrade` VALUES (4, 2001, 3000);
INSERT INTO `salgrade` VALUES (5, 3001, 9999);

SET FOREIGN_KEY_CHECKS = 1;

1. 获取每个部门最高薪水的人员名称

-- SELECT MAX(SAL) MAXSAL FROM emp GROUP BY DEPTNO;
SELECT e.ENAME,e.SAL,e.DEPTNO FROM emp e INNER JOIN (SELECT DEPTNO,MAX(SAL) MAXSAL FROM emp GROUP BY DEPTNO) tt on e.SAL = tt.MAXSAL and e.DEPTNO = tt.DEPTNO;

• 哪些人的薪水在部门平均水平以上

-- SELECT DEPTNO,AVG(SAL) avgSal FROM emp GROUP BY DEPTNO;

SELECT * FROM emp INNER JOIN (SELECT DEPTNO,AVG(SAL) avgSal FROM emp GROUP BY DEPTNO) tt on emp.SAL > tt.avgSal;

3. 获取部门中（所有人）的平均薪资水平

SELECT e.DEPTNO,avg(sg.GRADE) FROM emp e INNER JOIN salgrade sg on e.sal >= sg.LOSAL AND e.sal <= sg.HISAL GROUP BY e.DEPTNO;

4. 不准用组函数（Max），取得最高薪水

SELECT ENAME,JOB,SAL FROM emp ORDER BY SAL DESC LIMIT 0,1;

5. 取得平均薪水最高的部门的部门编号

SELECT DEPTNO ,AVG(SAL) avgSal FROM emp GROUP BY DEPTNO ORDER BY avgSal DESC LIMIT 1

6. 取得平均薪水最高的部门的部门名称

SELECT tt.DEPTNO,salgrade.GRADE FROM(SELECT DEPTNO ,AVG(SAL) avgSal FROM emp GROUP BY DEPTNO ORDER BY avgSal DESC LIMIT 1) tt INNER JOIN salgrade on tt.avgSal >= salgrade.LOSAL and tt.avgSal <= salgrade.HISAL

7. 求平均薪水的等级最低的部门的部门名称

SELECT dept.DNAME ,tt.DEPTNO,tt.avgSAl FROM (SELECT DEPTNO,AVG(SAL) avgSal FROM emp GROUP BY DEPTNO ) tt INNER JOIN dept WHERE tt.DEPTNO = dept.DEPTNO ORDER BY tt.avgSal LIMIT 0,1;

8. 取得比普通员工(员工代码没有在MGR字段上出现的)的最高薪水还要高的领导人姓名

SELECT ENAME FROM emp WHERE SAL > (SELECT MAX(SAL) FROM emp WHERE EMPNO NOT in (SELECT MGR FROM emp WHERE mgr is not NULL GROUP BY MGR))

9. 取得薪水最高的前五名员工

SELECT * FROM EMP ORDER BY SAL DESC LIMIT 5

10. 取得薪水最高的第六到第十名员工

SELECT * FROM emp ORDER BY SAL DESC LIMIT 5,5;

11. 取得最后入职的5名员工

SELECT * FROM emp ORDER BY HIREDATE DESC LIMIT 0,5;

12. 取得每个薪水等级有多少员工

SELECT tt.GRADE,COUNT(tt.DEPTNO) as count FROM (SELECT emp.DEPTNO , salgrade.GRADE FROM emp INNER JOIN salgrade on emp.SAL > salgrade.LOSAL and emp.SAL < salgrade.HISAL) tt GROUP BY tt.GRADE

13. 列出所有员工及领导的姓名

SELECT e1.ENAME,e2.ENAME FROM emp e1 LEFT JOIN emp e2 on e1.MGR = e2.EMPNO;

14. 列出受雇日期早于其直接上级的所有员工的编号,姓名,部门名称

SELECT tt.*,dept.DNAME FROM (SELECT e1.ENAME,e2.EMPNO MGRNO,e2.ENAME MGRNAME ,e2.DEPTNO FROM emp e1 LEFT JOIN emp e2 on e1.MGR = e2.EMPNO WHERE e1.HIREDATE < e2.HIREDATE) tt INNER JOIN dept on tt.DEPTNO = dept.DEPTNO 

15. 列出部门名称和这些部门的员工信息,同时列出那些没有员工的部门.

SELECT dept.DNAME,emp.* FROM emp RIGHT JOIN dept on dept.DEPTNO = emp.DEPTNO

总结 ：

JOIN 按照功能大致分为如下三类：
INNER JOIN（内连接,或等值连接）：获取两个表中字段匹配关系的记录。
LEFT JOIN（左连接）：获取左表所有记录，即使右表没有对应匹配的记录。
RIGHT JOIN（右连接）： 与 LEFT JOIN 相反，用于获取右表所有记录，即使左表没有对应匹配的记录。

16. 列出至少有5个员工的所有部门

SELECT dept.DEPTNO , dept.DNAME, tt.count FROM (SELECT DEPTNO,count(DEPTNO) count FROM emp GROUP BY DEPTNO  ) tt,dept WHERE dept.DEPTNO = tt.DEPTNO AND tt.count >= 5

17. 列出薪金比"SMITH"多的所有员工信息.

SELECT * FROM emp WHERE sal > ( SELECT sal FROM emp WHERE ENAME = "SMITH" )

18. 有"CLERK"(办事员)的姓名及其部门名称,部门的人数.

SELECT tt.ENAME,dept.DNAME, dd.count FROM ( SELECT * FRO![M emp WHERE JOB = "CLERK" ) tt INNER JOIN dept on tt)
DEPTNO = dept.DEPTNO INNER JOIN (SELECT DEPTNO,COUNT(DEPTNO) count FROM emp GROUP BY DEPTNO) dd on dd.DEPTNO = tt.DEPTNO;

19. 列出最低薪金大于1500的各种工作及从事此工作的全部雇员人数.

SELECT JOB ,COUNT(EMPNO) FROM emp GROUP BY JOB HAVING min(sal) > 1500

20. # 列出在部门"SALES"<销售部>工作的员工的姓名,假定不知道销售部的部门编号.思路

SELECT ENAME FROM emp WHERE DEPTNO =  (SELECT DEPTNO FROM dept WHERE DNAME = "SALES" )

21. 列出薪金高于公司平均薪金的所有员工,所在部门,上级领导,雇员的工资等级.

SELECT tt.ENAME ,tt.JOB ,dept.DNAME,tt.MGR,dd.grade FROM ( SELECT * FROM emp WHERE sal > ( SELECT avg(sal) FROM emp ) ) tt INNER JOIN dept on tt.DEPTNO = dept.DEPTNO INNER JOIN salgrade dd on tt.SAL > dd.LOSAL AND tt.SAL < dd.HISAL

22. 列出与"SCOTT"从事相同工作的所有员工及部门名称.

SELECT emp.ENAME,dept.DNAME FROM emp,dept WHERE JOB = ( SELECT JOB FROM emp WHERE ENAME = "SCOTT" ) AND dept.DEPTNO = emp.DEPTNO;

23. 列出薪金等于部门30中员工的薪金的其他员工的姓名和薪金.

SELECT * FROM emp WHERE sal in (SELECT SAL FROM emp WHERE DEPTNO = 30 ) AND DEPTNO != 30;

24. 列出薪金高于在部门30工作的所有员工的薪金的员工姓名和薪金.部门名称.

SELECT * FROM emp WHERE SAL >  ( SELECT max(SAL) maxsal FROM emp WHERE DEPTNO = 30 ) AND DEPTNO != 30

25. 列出在每个部门工作的员工数量,平均工资和平均服务期限.

SELECT DEPTNO , COUNT(EMPNO) count,AVG(sal) avgsal ,avg(  (to_days(  now()   ) - to_days
( hiredate ) ) / 365)  FROM emp GROUP BY DEPTNO ;

26. 列出所有员工的姓名、部门名称和工资。

SELECT emp.ENAME,dept.DNAME,emp.SAL FROM emp INNER JOIN dept on emp.DEPTNO = dept.DEPTNO;

28. 列出所有部门的详细信息和人数

SELECT * FROM dept INNER JOIN (SELECT DEPTNO,COUNT(EMPNO) FROM emp GROUP BY DEPTNO ) tt on dept.DEPTNO = tt.DEPTNO ;

29. 列出各种工作的最低工资及从事此工作的雇员姓名

SELECT emp.ENAME,tt.* FROM ( SELECT JOB,min(sal)  minsal FROM emp GROUP BY JOB ) tt ,emp WHERE tt.minsal = emp.SAL;

30. 列出各个部门的MANAGER(领导)的最低薪金

SELECT DEPTNO, min(SAL) FROM emp WHERE JOB = "MANAGER" GROUP BY DEPTNO;

31. 列出所有员工的年工资,按年薪从低到高排序

SELECT ENAME,(sal + IFNULL(COMM,0))*12 FROM emp ORDER BY sal DESC;

32. 求出员工领导的薪水超过3000的员工名称与领导名称

SELECT e1.ENAME empname,e2.ENAME mgrname FROM emp e1 INNER JOIN emp e2 on e1.MGR = e2.EMPNO WHERE e2.SAL > 3000