MySQL 作业题及答案

MySQL 测试题

一、表关系：

请创建如下表，并创建相关约束

创建表sql如下：

/*

Navicat MySQL Data Transfer

Source Server         : 192.168.118.14

Source Server Version : 50544

Source Host           : 192.168.118.14:3306

Source Database       : db3

Target Server Type    : MYSQL

Target Server Version : 50544

File Encoding         : 65001

Date: 2019-02-15 16:34:46

*/

SET FOREIGN_KEY_CHECKS=0;

-- ----------------------------

-- Table structure for class

-- ----------------------------

DROP TABLE IF EXISTS `class`;

CREATE TABLE `class` (

  `cid` int(11) NOT NULL AUTO_INCREMENT,

  `caption` varchar(32) DEFAULT NULL,

  PRIMARY KEY (`cid`),

  UNIQUE KEY `caption` (`caption`)

) ENGINE=InnoDB AUTO_INCREMENT=5 DEFAULT CHARSET=utf8;

-- ----------------------------

-- Records of class

-- ----------------------------

INSERT INTO `class` VALUES ('', '一年二班');

INSERT INTO `class` VALUES ('', '三年三班');

INSERT INTO `class` VALUES ('', '三年二班');

INSERT INTO `class` VALUES ('', '二年九班');

-- ----------------------------

-- Table structure for course

-- ----------------------------

DROP TABLE IF EXISTS `course`;

CREATE TABLE `course` (

  `cid` int(11) NOT NULL AUTO_INCREMENT,

  `cname` varchar(32) NOT NULL,

  `teacher_id` int(11) NOT NULL,

  PRIMARY KEY (`cid`),

  KEY `fk_course_teacher` (`teacher_id`),

  CONSTRAINT `fk_course_teacher` FOREIGN KEY (`teacher_id`) REFERENCES `teacher` (`tid`)

) ENGINE=InnoDB AUTO_INCREMENT=5 DEFAULT CHARSET=utf8;

-- ----------------------------

-- Records of course

-- ----------------------------

INSERT INTO `course` VALUES ('', '生物', '');

INSERT INTO `course` VALUES ('', '物理', '');

INSERT INTO `course` VALUES ('', '体育', '');

INSERT INTO `course` VALUES ('', '美术', '');

-- ----------------------------

-- Table structure for score

-- ----------------------------

DROP TABLE IF EXISTS `score`;

CREATE TABLE `score` (

  `sid` int(11) NOT NULL AUTO_INCREMENT,

  `student_id` int(11) NOT NULL,

  `course_id` int(11) NOT NULL,

  `number` int(11) NOT NULL,

  PRIMARY KEY (`sid`),

  UNIQUE KEY `student_id` (`student_id`,`course_id`),

  KEY `fk_score_course` (`course_id`),

  CONSTRAINT `fk_score_student` FOREIGN KEY (`student_id`) REFERENCES `student` (`sid`),

  CONSTRAINT `fk_score_course` FOREIGN KEY (`course_id`) REFERENCES `course` (`cid`)

) ENGINE=InnoDB AUTO_INCREMENT=66 DEFAULT CHARSET=utf8;

-- ----------------------------

-- Records of score

-- ----------------------------

INSERT INTO `score` VALUES ('', '', '', '');

INSERT INTO `score` VALUES ('', '', '', '');

INSERT INTO `score` VALUES ('', '', '', '');

INSERT INTO `score` VALUES ('', '', '', '');

INSERT INTO `score` VALUES ('', '', '', '');

INSERT INTO `score` VALUES ('', '', '', '');

INSERT INTO `score` VALUES ('', '', '', '');

INSERT INTO `score` VALUES ('', '', '', '');

INSERT INTO `score` VALUES ('', '', '', '');

INSERT INTO `score` VALUES ('', '', '', '');

INSERT INTO `score` VALUES ('', '', '', '');

INSERT INTO `score` VALUES ('', '', '', '');

INSERT INTO `score` VALUES ('', '', '', '');

INSERT INTO `score` VALUES ('', '', '', '');

INSERT INTO `score` VALUES ('', '', '', '');

INSERT INTO `score` VALUES ('', '', '', '');

INSERT INTO `score` VALUES ('', '', '', '');

INSERT INTO `score` VALUES ('', '', '', '');

INSERT INTO `score` VALUES ('', '', '', '');

INSERT INTO `score` VALUES ('', '', '', '');

INSERT INTO `score` VALUES ('', '', '', '');

INSERT INTO `score` VALUES ('', '', '', '');

INSERT INTO `score` VALUES ('', '', '', '');

INSERT INTO `score` VALUES ('', '', '', '');

INSERT INTO `score` VALUES ('', '', '', '');

INSERT INTO `score` VALUES ('', '', '', '');

INSERT INTO `score` VALUES ('', '', '', '');

INSERT INTO `score` VALUES ('', '', '', '');

INSERT INTO `score` VALUES ('', '', '', '');

INSERT INTO `score` VALUES ('', '', '', '');

INSERT INTO `score` VALUES ('', '', '', '');

INSERT INTO `score` VALUES ('', '', '', '');

INSERT INTO `score` VALUES ('', '', '', '');

INSERT INTO `score` VALUES ('', '', '', '');

INSERT INTO `score` VALUES ('', '', '', '');

INSERT INTO `score` VALUES ('', '', '', '');

INSERT INTO `score` VALUES ('', '', '', '');

INSERT INTO `score` VALUES ('', '', '', '');

INSERT INTO `score` VALUES ('', '', '', '');

INSERT INTO `score` VALUES ('', '', '', '');

INSERT INTO `score` VALUES ('', '', '', '');

INSERT INTO `score` VALUES ('', '', '', '');

INSERT INTO `score` VALUES ('', '', '', '');

INSERT INTO `score` VALUES ('', '', '', '');

INSERT INTO `score` VALUES ('', '', '', '');

INSERT INTO `score` VALUES ('', '', '', '');

INSERT INTO `score` VALUES ('', '', '', '');

INSERT INTO `score` VALUES ('', '', '', '');

INSERT INTO `score` VALUES ('', '', '', '');

INSERT INTO `score` VALUES ('', '', '', '');

INSERT INTO `score` VALUES ('', '', '', '');

INSERT INTO `score` VALUES ('', '', '', '');

-- ----------------------------

-- Table structure for student

-- ----------------------------

DROP TABLE IF EXISTS `student`;

CREATE TABLE `student` (

  `sid` int(11) NOT NULL AUTO_INCREMENT,

  `gender` varchar(2) NOT NULL,

  `class_id` int(11) NOT NULL,

  `sname` varchar(32) NOT NULL,

  PRIMARY KEY (`sid`),

  KEY `fk_student_class` (`class_id`),

  CONSTRAINT `fk_student_class` FOREIGN KEY (`class_id`) REFERENCES `class` (`cid`)

) ENGINE=InnoDB AUTO_INCREMENT=18 DEFAULT CHARSET=utf8;

-- ----------------------------

-- Records of student

-- ----------------------------

INSERT INTO `student` VALUES ('', '男', '', '理解');

INSERT INTO `student` VALUES ('', '女', '', '钢蛋');

INSERT INTO `student` VALUES ('', '男', '', '张三');

INSERT INTO `student` VALUES ('', '男', '', '张一');

INSERT INTO `student` VALUES ('', '女', '', '张二');

INSERT INTO `student` VALUES ('', '男', '', '张四');

INSERT INTO `student` VALUES ('', '女', '', '铁锤');

INSERT INTO `student` VALUES ('', '男', '', '李三');

INSERT INTO `student` VALUES ('', '男', '', '李一');

INSERT INTO `student` VALUES ('', '女', '', '李二');

INSERT INTO `student` VALUES ('', '男', '', '李四');

INSERT INTO `student` VALUES ('', '女', '', '如花');

INSERT INTO `student` VALUES ('', '男', '', '刘三');

INSERT INTO `student` VALUES ('', '男', '', '刘一');

INSERT INTO `student` VALUES ('', '女', '', '刘二');

INSERT INTO `student` VALUES ('', '男', '', '刘四');

INSERT INTO `student` VALUES ('', '女', '', '张三');

-- ----------------------------

-- Table structure for teacher

-- ----------------------------

DROP TABLE IF EXISTS `teacher`;

CREATE TABLE `teacher` (

  `tid` int(11) NOT NULL AUTO_INCREMENT,

  `tname` varchar(32) NOT NULL,

  PRIMARY KEY (`tid`)

) ENGINE=InnoDB AUTO_INCREMENT=6 DEFAULT CHARSET=utf8;

-- ----------------------------

-- Records of teacher

-- ----------------------------

INSERT INTO `teacher` VALUES ('', '张磊老师');

INSERT INTO `teacher` VALUES ('', '李平老师');

INSERT INTO `teacher` VALUES ('', '刘海燕老师');

INSERT INTO `teacher` VALUES ('', '朱云海老师');

INSERT INTO `teacher` VALUES ('', '李杰老师');

表结构及数据

二、表操作及答案

1. 查询“生物”课程比“物理”课程成绩高的所有学生的学号

select A.student_id, sw, wl from

(SELECT score.student_id, number as sw from score LEFT JOIN course on score.course_id = course.cid where course.cname = '生物') as     A

LEFT JOIN

(SELECT score.student_id, number as wl from score LEFT JOIN course on score.course_id = course.cid where course.cname = '物理') as B

on A.student_id = B.student_id where sw > wl

2. 查询平均成绩大于60分的同学的学号和平均成绩

SELECT student_id, avg(number) from score GROUP BY score.student_id HAVING avg(number) > 60

3. 查询所有同学的学号、姓名、选课数、总成绩

SELECT score.student_id, student.sname, count(score.course_id), sum(number) from score

LEFT JOIN student on score.student_id = student.sid

GROUP BY score.student_id

4. 查询姓“李”的老师的个数

SELECT count(1) from teacher where teacher.tname like '李%'

5. 查询没学过“李平老师”课的同学的学号、姓名

SELECT sid, sname from student where student.sid  not in (

SELECT DISTINCT score.student_id from score where score.course_id in (

SELECT course.cid from course

LEFT JOIN teacher on course.teacher_id = teacher.tid

where teacher.tname = '李平老师'))

6. 查询学过“001”并且也学过编号“002”课程的同学的学号、姓名

SELECT sid, sname from student where student.sid in (

SELECT score.student_id from score where score.course_id = 1 or score.course_id = 2

GROUP BY score.student_id HAVING count(1) > 1);

7. 查询学过“李平老师”老师所教的所有课的同学的学号、姓名

SELECT sid, sname from student where student.sid in (

SELECT score.student_id from score where score.course_id in

(SELECT cid from course LEFT JOIN teacher on course.teacher_id = teacher.tid where teacher.tname = '李平老师')

GROUP BY score.student_id HAVING count(1) = (SELECT count(1) from course

LEFT JOIN teacher on course.teacher_id = teacher.tid where teacher.tname = '李平老师'))

8. 查询课程编号“002”的成绩比课程编号“001”课程低的所有同学的学号、姓名

SELECT sid, sname from student where student.sid in (

select A.student_id from

(select student_id, number as num_2 from score where score.course_id = 2) as A

LEFT JOIN

(select student_id, number as num_1 from score where score.course_id = 1) as B

on A.student_id = B.student_id where A.num_2 < B.num_1)

9. 查询有课程成绩小于60分的同学的学号、姓名

SELECT DISTINCT student.sid, student.sname from score

LEFT JOIN student on score.student_id = student.sid where score.number < 60;

10. 查询没有学全所有课的同学的学号、姓名

SELECT sid, sname from student where sid in (

SELECT score.student_id from score GROUP BY student_id HAVING count(1) != (SELECT count(1) from course))

11. 查询至少有一门课与学号为“1”的同学所学相同的同学的学号和姓名

SELECT sid, sname from student where sid in (

SELECT DISTINCT student_id from score where score.course_id in (SELECT course_id from score where student_id = 1))

and sid != 1;

12. 查询至少学过学号为“1”同学所有课的其他同学学号和姓名 *****

SELECT sid, sname from student where sid in (

SELECT student_id from score where score.course_id in (SELECT course_id from score WHERE score.student_id =1 )

GROUP BY student_id HAVING count(1) = (SELECT count(1) from score WHERE score.student_id =1))

13. 查询和“1”号的同学学习的课程完全相同的其他同学学号和姓名

SELECT student.sid, sname from score

LEFT JOIN student on score.student_id = student.sid

where score.student_id in (

SELECT score.student_id from score where score.student_id != 1 GROUP BY student_id HAVING count(1) = (SELECT count(1) from score where score.student_id = 1)

and course_id in (SELECT course_id from score where score.course_id in (SELECT course_id from score where score.student_id = 1)

GROUP BY student_id HAVING count(1) = (SELECT count(1) from score where score.student_id = 1)

))

14. 删除学习“叶平”老师课的score表记录

DELETE from score where course_id in (

SELECT course.cid from course LEFT JOIN teacher on course.teacher_id = teacher.tid where teacher.tname = '李平老师');

15. 向 score 表中插入一些记录，这些记录要求符合以下条件：①没有上过编号“001”课程的同学学号；②插入“001”号课程的平均成绩

INSERT into score (student_id, course_id, number)

SELECT sid, 1, (SELECT avg(number) from score where score.course_id = 1)

from student where student.sid not in (select student_id from score where score.course_id = 1)

16. 按平均成绩从低到高显示所有学生的“生物”、“物理”、“体育”三门的课程成绩，按如下形式显示：学生ID,生物、物理、体育,有效课程数,有效平均分

SELECT sc.student_id,

(SELECT avg(number) from score LEFT JOIN course on score.course_id = course.cid where score.student_id = sc.student_id and course.cname = '生物') as sw,

(SELECT avg(number) from score LEFT JOIN course on score.course_id = course.cid where score.student_id = sc.student_id and course.cname = '物理') as wl,

(SELECT avg(number) from score LEFT JOIN course on score.course_id = course.cid where score.student_id = sc.student_id and course.cname = '体育') as ty,

count(sc.course_id),

avg(sc.number) as avg_n

from score sc GROUP BY sc.student_id  ORDER BY avg_n asc;

17. 查询各科成绩最高和最低的分：以如下形式显示：课程ID，最高分，最低分

select course_id, max(number), min(number) from score GROUP BY course_id

18. 按各科平均成绩从低到高和及格率的百分数从高到低顺序

SELECT score.course_id, avg(number) as avg_n,

(sum(case when score.number > 60 then 1 else 0 end) / count(1) * 100) as percent

from score GROUP BY score.course_id ORDER BY avg_n asc, percent desc;

19. 课程平均分从高到低显示（现实任课老师）

SELECT score.course_id, avg(score.number) as avg_n, teacher.tname from score

LEFT JOIN course on score.course_id = course.cid

LEFT JOIN teacher on course.teacher_id = teacher.tid

GROUP BY score.course_id ORDER BY avg_n desc;

20. 查询各科成绩前三名的记录:(不考虑成绩并列情况)

SELECT

sc.course_id,

(SELECT number from score where score.course_id = sc.course_id ORDER BY number desc limit 0,1) as first_num,

(SELECT number from score where score.course_id = sc.course_id GROUP BY number ORDER BY number desc limit 1,1) as second_num,

(SELECT number from score where score.course_id = sc.course_id GROUP BY number ORDER BY number desc limit 2,1) as third_num

from score sc GROUP BY sc.course_id

21. 查询每门课程被选修的学生数

SELECT course_id, count(student_id) from score GROUP BY course_id

22. 查询出只选修了一门课程的全部学生的学号和姓名

SELECT student.sid, student.sname from score

LEFT JOIN student on score.student_id = student.sid

GROUP BY student_id HAVING count(score.course_id) =1 ;

23. 查询男生、女生的人数

SELECT * from

(SELECT count(1) as boy from student where student.gender = '男') as A,

(SELECT count(1) as girl from student where student.gender = '女') as B

24. 查询姓“张”的学生名单

SELECT * from student where student.sname like '张%'

25. 查询同名同姓学生名单，并统计同名人数

SELECT sname, count(sname) from student GROUP BY sname HAVING count(1) > 1;

26. 查询每门课程的平均成绩，结果按平均成绩升序排列，平均成绩相同时，按课程号降序排列

SELECT course_id, avg(number) as avg_n from score GROUP BY course_id ORDER BY avg_n asc, course_id desc;

27. 查询平均成绩大于80的所有学生的学号、姓名和平均成绩

SELECT score.student_id, student.sname, avg(number) from score

LEFT JOIN student on score.student_id = student.sid

GROUP BY student_id HAVING avg(number) > 80;

28. 查询课程名称为“生物”，且分数低于60的学生姓名和分数

SELECT * from score

LEFT JOIN student on score.student_id = student.sid

where score.number < 60 and score.course_id in (SELECT cid from course where course.cname = '生物')

29. 查询课程编号为003且课程成绩在80分以上的学生的学号和姓名

SELECT student.sid, student.sname from score

LEFT JOIN student on score.student_id = student.sid

where score.course_id = 3 and score.number > 80;

30. 求选了课程的学生人数

SELECT count(DISTINCT student_id) from score where score.course_id is not null;

31. 查询选修刘海燕老师所授课程的学生中，成绩最高的学生姓名及其成绩

SELECT student.sname, max(score.number) from score

LEFT JOIN student on score.student_id = student.sid

where score.course_id in (SELECT cid from course

LEFT JOIN teacher on course.teacher_id = teacher.tid where teacher.tname = '刘海燕老师')

32. 查询各个课程及相应的选修人数

SELECT course_id, count(1) from score GROUP BY course_id

33. 查询不同课程但成绩相同的学生的学号、课程号、学生成绩

SELECT DISTINCT s1.course_id, s2.course_id, s1.number, s2.number from score as s1, score as s2

where s1.number = s2.number and s1.course_id != s2.course_id order by s1.course_id

34. 查询每门课程成绩最好的前两名

SELECT sc.course_id,

(SELECT number as f_n from score where course_id = sc.course_id ORDER BY number desc limit 0, 1) as first_num,

(SELECT number as f_n from score where course_id = sc.course_id GROUP BY number ORDER BY number desc limit 1, 1) as second_num

from score sc GROUP BY sc.course_id

35. 检索至少选修两门课程的学生学号

SELECT student_id, count(1) from score GROUP BY student_id HAVING count(1) > 1;

36. 查询全部学生都选修的课程的课程号和课程名

SELECT score.course_id, course.cname from score

LEFT JOIN course on score.course_id = course.cid

GROUP BY course_id HAVING count(1) = (SELECT count(1) from student)

37. 查询没学过李平老师讲授的任一门课程的学生姓名

SELECT sid, sname from student where sid not in (

SELECT DISTINCT student_id from score where score.course_id in (

SELECT cid from course

LEFT JOIN teacher on course.teacher_id = teacher.tid where teacher.tname = '李平老师'))

38. 查询两门以上不及格课程的同学的学号及其平均成绩

SELECT sc.student_id, (SELECT avg(number) from score where score.student_id = sc.student_id) as avg_n from score sc

where sc.number < 60 GROUP BY student_id HAVING count(1) > 1;

39. 检索“004”课程分数小于60，按分数降序排列的同学学号

SELECT student_id from score where score.course_id = 4 and score.number < 60 ORDER BY score.number desc;

40. 删除“002”同学的“001”课程的成绩

DELETE from score where score.student_id = 2 and score.course_id = 1;

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