python之数据库
发表于：2025-01-20 作者：千家信息网编辑
千家信息网最后更新 2025年01月20日，'''# 作业内容1、查询所有的课程的名称以及对应的任课老师姓名2、查询学生表中男女生各有多少人3、查询物理成绩等于100的学生的姓名4、查询平均成绩大于八十分的同学的姓名和平均成绩5、查询所有学生的
千家信息网最后更新 2025年01月20日python之数据库
'''# 作业内容1、查询所有的课程的名称以及对应的任课老师姓名2、查询学生表中男女生各有多少人3、查询物理成绩等于100的学生的姓名4、查询平均成绩大于八十分的同学的姓名和平均成绩5、查询所有学生的学号，姓名，选课数，总成绩6、 查询姓李老师的个数7、 查询没有报李平老师课的学生姓名8、 查询物理课程比生物课程高的学生的学号9、 查询没有同时选修物理课程和体育课程的学生姓名10、查询挂科超过两门(包括两门)的学生姓名和班级'''博客链接：https://blog.51cto.com/11019859/2074536# 创建库和库表，并插入数据'''班级表：class课程表：course成绩表：score学生表：student老师表：teacher'''mysql> create database sqlexam;Query OK, 1 row affected (0.01 sec)mysql> use sqlexamDatabase changedmysql>mysql> SET NAMES utf8;Query OK, 0 rows affected (0.01 sec)mysql> SET FOREIGN_KEY_CHECKS = 0;Query OK, 0 rows affected (0.00 sec)mysql> DROP TABLE IF EXISTS `class`;Query OK, 0 rows affected, 1 warning (0.00 sec)mysql> CREATE TABLE `class` ( -> `cid` int(11) NOT NULL AUTO_INCREMENT, -> `caption` varchar(32) NOT NULL, -> PRIMARY KEY (`cid`) -> ) ENGINE=InnoDB AUTO_INCREMENT=5 DEFAULT CHARSET=utf8;Query OK, 0 rows affected (0.04 sec)mysql> INSERT INTO `class` VALUES ('1', '三年二班'), ('2', '三年三班'), ('3', ' 一年二班'), ('4', '二年九班');Query OK, 4 rows affected (0.00 sec)Records: 4 Duplicates: 0 Warnings: 0mysql> DROP TABLE IF EXISTS `course`;Query OK, 0 rows affected, 1 warning (0.00 sec)mysql> 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;Query OK, 0 rows affected (0.04 sec)mysql> INSERT INTO `course` VALUES ('1', '生物', '1'), ('2', '物理', '2'), ('3', '体育', '3'), ('4', '美术', '2');Query OK, 4 rows affected (0.01 sec)Records: 4 Duplicates: 0 Warnings: 0mysql> DROP TABLE IF EXISTS `score`;Query OK, 0 rows affected, 1 warning (0.00 sec)mysql> CREATE TABLE `score` ( -> `sid` int(11) NOT NULL AUTO_INCREMENT, -> `student_id` int(11) NOT NULL, -> `course_id` int(11) NOT NULL, -> `num` int(11) NOT NULL, -> PRIMARY KEY (`sid`), -> KEY `fk_score_student` (`student_id`), -> KEY `fk_score_course` (`course_id`), -> CONSTRAINT `fk_score_course` FOREIGN KEY (`course_id`) REFERENCES `course` (`cid`), -> CONSTRAINT `fk_score_student` FOREIGN KEY (`student_id`) REFERENCES `student` (`sid`) -> ) ENGINE=InnoDB AUTO_INCREMENT=53 DEFAULT CHARSET=utf8;Query OK, 0 rows affected (0.02 sec)mysql> INSERT INTO `score` VALUES ('1', '1', '1', '10'), ('2', '1', '2', '9'), ('5', '1', '4', '66'), ('6', '2', '1', '8'), ('8', '2', '3', '68'), ('9', '2', '4', '99'), ('10', '3', '1', '77'), ('11', '3', '2', '66'), ('12', '3', '3', '87'), ('13', '3', '4', '99'), ('14', '4', '1', '79'), ('15', '4', '2', '11'), ('16', '4', '3', '67'), ('17', '4', '4', '100'), ('18', '5', '1', '79'), ('19', '5', '2', '11'), ('20', '5', '3', '67'), ('21', '5', '4', '100'), ('22', '6', '1', '9'), ('23', '6', '2', '100'), ('24', '6', '3', '67'), ('25', '6', '4', '100'), ('26', '7', '1', '9'), ('27', '7', '2', '100'), ('28', '7', '3', '67'), ('29', '7', '4', '88'), ('30', '8', '1', '9'), ('31', '8', '2', '100'), ('32', '8', '3', '67'), ('33', '8', '4', '88'), ('34', '9', '1', '91'), ('35', '9', '2', '88'), ('36', '9', '3', '67'), ('37', '9', '4', '22'), ('38', '10', '1', '90'), ('39', '10', '2', '77'), ('40', '10', '3', '43'), ('41', '10', '4', '87'), ('42', '11', '1', '90'), ('43', '11', '2', '77'), ('44', '11', '3', '43'), ('45', '11', '4', '87'), ('46', '12', '1', '90'), ('47', '12', '2', '77'), ('48', '12', '3', '43'), ('49', '12', '4', '87'), ('52', '13', '3', '87');Query OK, 47 rows affected (0.01 sec)Records: 47 Duplicates: 0 Warnings: 0mysql> DROP TABLE IF EXISTS `student`;Query OK, 0 rows affected, 1 warning (0.00 sec)mysql> CREATE TABLE `student` ( -> `sid` int(11) NOT NULL AUTO_INCREMENT, -> `gender` char(1) NOT NULL, -> `class_id` int(11) NOT NULL, -> `sname` varchar(32) NOT NULL, -> PRIMARY KEY (`sid`), -> KEY `fk_class` (`class_id`), -> CONSTRAINT `fk_class` FOREIGN KEY (`class_id`) REFERENCES `class` (`cid`) -> ) ENGINE=InnoDB AUTO_INCREMENT=17 DEFAULT CHARSET=utf8;Query OK, 0 rows affected (0.02 sec)mysql> INSERT INTO `student` VALUES ('1', '男', '1', '理解'), ('2', '女', '1', '钢蛋'), ('3', '男', '1', '张三'), ('4', '男', '1', '张一'), ('5', '女', '1', '张二'), ('6', '男', '1', '张四'), ('7', '女', '2', '铁锤'), ('8', '男', '2', '李三'), ('9', '男', '2', '李一'), ('10', '女', '2', '李二'), ('11', '男', '2', '李四'), ('12', '女', '3', '如花'), ('13', '男', '3', '刘三'), ('14', '男', '3', '刘 一'), ('15', '女', '3', '刘二'), ('16', '男', '3', '刘四');Query OK, 16 rows affected (0.01 sec)Records: 16 Duplicates: 0 Warnings: 0mysql> DROP TABLE IF EXISTS `teacher`;Query OK, 0 rows affected, 1 warning (0.00 sec)mysql> 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;Query OK, 0 rows affected (0.02 sec)mysql> INSERT INTO `teacher` VALUES ('1', '张磊老师'), ('2', '李平老师'), ('3', '刘海燕老师'), ('4', '朱云海老师'), ('5', '李杰老师');Query OK, 5 rows affected (0.00 sec)Records: 5 Duplicates: 0 Warnings: 0mysql> SET FOREIGN_KEY_CHECKS = 1;Query OK, 0 rows affected (0.00 sec)mysql> show tables;+-------------------+| Tables_in_sqlexam |+-------------------+| class || course || score || student || teacher |+-------------------+5 rows in set (0.00 sec)# 1、查询所有的课程的名称以及对应的任课老师姓名mysql> SELECT -> course.cname, -> teacher.tname -> FROM -> course -> INNER JOIN teacher ON course.teacher_id = teacher.tid;+--------+-----------------+| cname | tname |+--------+-----------------+| 生物 | 张磊老师 || 物理 | 李平老师 || 美术 | 李平老师 || 体育 | 刘海燕老师 |+--------+-----------------+4 rows in set (0.01 sec)# 2、查询学生表中男女生各有多少人mysql> SELECT -> gender 性别, -> count(1) 人数 -> FROM -> student -> GROUP BY -> gender;+--------+--------+| 性别 | 人数 |+--------+--------+| 女 | 6 || 男 | 10 |+--------+--------+2 rows in set (0.00 sec)# 3、查询物理成绩等于100的学生的姓名mysql> SELECT -> student.sname -> FROM -> student -> WHERE -> sid IN ( -> SELECT -> student_id -> FROM -> score -> INNER JOIN course ON score.course_id = course.cid -> WHERE -> course.cname = '物理' -> AND score.num = 100 -> );+--------+| sname |+--------+| 张四 || 铁锤 || 李三 |+--------+3 rows in set (0.00 sec)# 4、查询平均成绩大于八十分的同学的姓名和平均成绩mysql> SELECT -> student.sname, -> t1.avg_num -> FROM -> student -> INNER JOIN ( -> SELECT -> student_id, -> avg(num) AS avg_num -> FROM -> score -> GROUP BY -> student_id -> HAVING -> avg(num) > 80 -> ) AS t1 ON student.sid = t1.student_id;+--------+---------+| sname | avg_num |+--------+---------+| 张三 | 82.2500 || 刘三 | 87.0000 |+--------+---------+2 rows in set (0.00 sec)# 5、查询所有学生的学号，姓名，选课数，总成绩mysql> SELECT -> student.sid, -> student.sname, -> t1.course_num, -> t1.total_num -> FROM -> student -> LEFT JOIN ( -> SELECT -> student_id, -> COUNT(course_id) course_num, -> sum(num) total_num -> FROM -> score -> GROUP BY -> student_id -> ) AS t1 ON student.sid = t1.student_id;+-----+--------+------------+-----------+| sid | sname | course_num | total_num |+-----+--------+------------+-----------+| 1 | 理解 | 3 | 85 || 2 | 钢蛋 | 3 | 175 || 3 | 张三 | 4 | 329 || 4 | 张一 | 4 | 257 || 5 | 张二 | 4 | 257 || 6 | 张四 | 4 | 276 || 7 | 铁锤 | 4 | 264 || 8 | 李三 | 4 | 264 || 9 | 李一 | 4 | 268 || 10 | 李二 | 4 | 297 || 11 | 李四 | 4 | 297 || 12 | 如花 | 4 | 297 || 13 | 刘三 | 1 | 87 || 14 | 刘一 | NULL | NULL || 15 | 刘二 | NULL | NULL || 16 | 刘四 | NULL | NULL |+-----+--------+------------+-----------+16 rows in set (0.00 sec)# 6、 查询姓李老师的个数mysql> SELECT -> count(tid) -> FROM -> teacher -> WHERE -> tname LIKE '李%';+------------+| count(tid) |+------------+| 2 |+------------+1 row in set (0.00 sec)# 7、 查询没有报李平老师课的学生姓名mysql> SELECT -> student.sname -> FROM -> student -> WHERE -> sid NOT IN ( -> SELECT DISTINCT -> student_id -> FROM -> score -> WHERE -> course_id IN ( -> SELECT -> course.cid -> FROM -> course -> INNER JOIN teacher ON course.teacher_id = teacher.tid -> WHERE -> teacher.tname = '李平老师' -> ) -> );+--------+| sname |+--------+| 刘三 || 刘一 || 刘二 || 刘四 |+--------+4 rows in set (0.00 sec)# 8、 查询物理课程比生物课程高的学生的学号mysql> SELECT -> t1.student_id -> FROM -> ( -> SELECT -> student_id, -> num -> FROM -> score -> WHERE -> course_id = ( -> SELECT -> cid -> FROM -> course -> WHERE -> cname = '物理' -> ) -> ) AS t1 -> INNER JOIN ( -> SELECT -> student_id, -> num -> FROM -> score -> WHERE -> course_id = ( -> SELECT -> cid -> FROM -> course -> WHERE -> cname = '生物' -> ) -> ) AS t2 ON t1.student_id = t2.student_id -> WHERE -> t1.num > t2.num;+------------+| student_id |+------------+| 6 || 7 || 8 |+------------+3 rows in set (0.00 sec)# 9、 查询没有同时选修物理课程和体育课程的学生姓名mysql> SELECT -> student.sname -> FROM -> student -> WHERE -> sid IN ( -> SELECT -> student_id -> FROM -> score -> WHERE -> course_id IN ( -> SELECT -> cid -> FROM -> course -> WHERE -> cname = '物理' -> OR cname = '体育' -> ) -> GROUP BY -> student_id -> HAVING -> COUNT(course_id) = 1 -> );+--------+| sname |+--------+| 理解 || 钢蛋 || 刘三 |+--------+3 rows in set (0.00 sec)# 10、查询挂科超过两门(包括两门)的学生姓名和班级mysql> SELECT -> student.sname, -> class.caption -> FROM -> student -> INNER JOIN ( -> SELECT -> student_id -> FROM -> score -> WHERE -> num < 60 -> GROUP BY -> student_id -> HAVING -> count(course_id) >= 2 -> ) AS t1 -> INNER JOIN class ON student.sid = t1.student_id -> AND student.class_id = class.cid;+--------+--------------+| sname | caption |+--------+--------------+| 理解 | 三年二班 |+--------+--------------+1 row in set (0.00 sec)# 11、查询选修了所有课程的学生姓名mysql> SELECT -> student.sname -> FROM -> student -> WHERE -> sid IN ( -> SELECT -> student_id -> FROM -> score -> GROUP BY -> student_id -> HAVING -> COUNT(course_id) = (SELECT count(cid) FROM course) -> );+--------+| sname |+--------+| 张三 || 张一 || 张二 || 张四 || 铁锤 || 李三 || 李一 || 李二 || 李四 || 如花 |+--------+10 rows in set (0.01 sec)# 12、查询李平老师教的课程的所有成绩记录mysql> SELECT -> * -> FROM -> score -> WHERE -> course_id IN ( -> SELECT -> cid -> FROM -> course -> INNER JOIN teacher ON course.teacher_id = teacher.tid -> WHERE -> teacher.tname = '李平老师' -> );+-----+------------+-----------+-----+| sid | student_id | course_id | num |+-----+------------+-----------+-----+| 2 | 1 | 2 | 9 || 11 | 3 | 2 | 66 || 15 | 4 | 2 | 11 || 19 | 5 | 2 | 11 || 23 | 6 | 2 | 100 || 27 | 7 | 2 | 100 || 31 | 8 | 2 | 100 || 35 | 9 | 2 | 88 || 39 | 10 | 2 | 77 || 43 | 11 | 2 | 77 || 47 | 12 | 2 | 77 || 5 | 1 | 4 | 66 || 9 | 2 | 4 | 99 || 13 | 3 | 4 | 99 || 17 | 4 | 4 | 100 || 21 | 5 | 4 | 100 || 25 | 6 | 4 | 100 || 29 | 7 | 4 | 88 || 33 | 8 | 4 | 88 || 37 | 9 | 4 | 22 || 41 | 10 | 4 | 87 || 45 | 11 | 4 | 87 || 49 | 12 | 4 | 87 |+-----+------------+-----------+-----+23 rows in set (0.00 sec)# 13、查询全部学生都选修了的课程号和课程名mysql> SELECT -> cid, -> cname -> FROM -> course -> WHERE -> cid IN ( -> SELECT -> course_id -> FROM -> score -> GROUP BY -> course_id -> HAVING -> COUNT(student_id) = ( -> SELECT -> COUNT(sid) -> FROM -> student -> ) -> );Empty set (0.00 sec)# 14、查询每门课程被选修的次数mysql> SELECT -> course_id, -> COUNT(student_id) -> FROM -> score -> GROUP BY -> course_id;+-----------+-------------------+| course_id | COUNT(student_id) |+-----------+-------------------+| 1 | 12 || 2 | 11 || 3 | 12 || 4 | 12 |+-----------+-------------------+4 rows in set (0.00 sec)# 15、查询只选修了一门课程的学生姓名和学号mysql> SELECT -> sid, -> sname -> FROM -> student -> WHERE -> sid IN ( -> SELECT -> student_id -> FROM -> score -> GROUP BY -> student_id -> HAVING -> COUNT(course_id) = 1 -> );+-----+--------+| sid | sname |+-----+--------+| 13 | 刘三 |+-----+--------+1 row in set (0.00 sec)# 16、查询所有学生考出的成绩并按从高到低排序（成绩去重）mysql> SELECT DISTINCT num FROM score ORDER BY num DESC;+-----+| num |+-----+| 100 || 99 || 91 || 90 || 88 || 87 || 79 || 77 || 68 || 67 || 66 || 43 || 22 || 11 || 10 || 9 || 8 |+-----+17 rows in set (0.00 sec)#17、查询平均成绩大于85的学生姓名和平均成绩mysql> SELECT -> sname, -> t1.avg_num -> FROM -> student -> INNER JOIN ( -> SELECT -> student_id, -> avg(num) avg_num -> FROM -> score -> GROUP BY -> student_id -> HAVING -> AVG(num) > 85 -> ) t1 ON student.sid = t1.student_id;+--------+---------+| sname | avg_num |+--------+---------+| 刘三 | 87.0000 |+--------+---------+1 row in set (0.00 sec)# 18、查询生物成绩不及格的学生姓名和对应生物分数mysql> SELECT -> sname,low_num -> FROM -> student -> INNER JOIN ( SELECT student_id, num low_num FROM score WHERE course_id = 1 GROUP BY student_id HAVING num < 60 ) t1 ON student.sid = t1.student_id;+--------+---------+| sname | low_num |+--------+---------+| 理解 | 10 || 钢蛋 | 8 || 张四 | 9 || 铁锤 | 9 || 李三 | 9 |+--------+---------+5 rows in set (0.00 sec)#19、查询在所有选修了李平老师课程的学生中，这些课程(李平老师的课程，不是所有课程)平均成绩最高的学生姓名mysql> SELECT -> sname -> FROM -> student -> WHERE -> sid = ( -> SELECT -> student_id -> FROM -> score -> WHERE -> course_id IN ( -> SELECT -> course.cid -> FROM -> course -> INNER JOIN teacher ON course.teacher_id = teacher.tid -> WHERE -> teacher.tname = '李平老师' -> ) -> GROUP BY -> student_id -> ORDER BY -> AVG(num) DESC -> LIMIT 1 -> );+--------+| sname |+--------+| 张四 |+--------+1 row in set (0.00 sec)# 20、查询每门课程成绩最好的前两名学生姓名mysql> SELECT -> * -> FROM -> score -> ORDER BY -> course_id, -> num DESC;+-----+------------+-----------+-----+| sid | student_id | course_id | num |+-----+------------+-----------+-----+| 34 | 9 | 1 | 91 || 46 | 12 | 1 | 90 || 42 | 11 | 1 | 90 || 38 | 10 | 1 | 90 || 14 | 4 | 1 | 79 || 18 | 5 | 1 | 79 || 10 | 3 | 1 | 77 || 1 | 1 | 1 | 10 || 30 | 8 | 1 | 9 || 26 | 7 | 1 | 9 || 22 | 6 | 1 | 9 || 6 | 2 | 1 | 8 || 31 | 8 | 2 | 100 || 23 | 6 | 2 | 100 || 27 | 7 | 2 | 100 || 35 | 9 | 2 | 88 || 47 | 12 | 2 | 77 || 43 | 11 | 2 | 77 || 39 | 10 | 2 | 77 || 11 | 3 | 2 | 66 || 19 | 5 | 2 | 11 || 15 | 4 | 2 | 11 || 2 | 1 | 2 | 9 || 52 | 13 | 3 | 87 || 12 | 3 | 3 | 87 || 8 | 2 | 3 | 68 || 20 | 5 | 3 | 67 || 36 | 9 | 3 | 67 || 16 | 4 | 3 | 67 || 24 | 6 | 3 | 67 || 32 | 8 | 3 | 67 || 28 | 7 | 3 | 67 || 48 | 12 | 3 | 43 || 44 | 11 | 3 | 43 || 40 | 10 | 3 | 43 || 21 | 5 | 4 | 100 || 17 | 4 | 4 | 100 || 25 | 6 | 4 | 100 || 9 | 2 | 4 | 99 || 13 | 3 | 4 | 99 || 29 | 7 | 4 | 88 || 33 | 8 | 4 | 88 || 41 | 10 | 4 | 87 || 49 | 12 | 4 | 87 || 45 | 11 | 4 | 87 || 5 | 1 | 4 | 66 || 37 | 9 | 4 | 22 |+-----+------------+-----------+-----+47 rows in set (0.00 sec)
查询
学生
老师
姓名
课程
成绩
物理
李平
生物
体育
学号
铁锤
张三
班级
李一
李二
李四
如花
个数
人数
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