python之數據庫
阿新 • • 發佈：2018-03-02
python mysql
# 作業內容
‘‘‘
1、查詢所有的課程的名稱以及對應的任課老師姓名
2、查詢學生表中男女生各有多少人
3、查詢物理成績等於100的學生的姓名
4、查詢平均成績大於八十分的同學的姓名和平均成績
5、查詢所有學生的學號，姓名，選課數，總成績
6、 查詢姓李老師的個數
7、 查詢沒有報李平老師課的學生姓名
8、 查詢物理課程比生物課程高的學生的學號
9、 查詢沒有同時選修物理課程和體育課程的學生姓名
10、查詢掛科超過兩門(包括兩門)的學生姓名和班級
‘‘‘
# 創建庫和庫表，並插入數據
‘‘‘
班級表：class
課程表：course
成績表：score
學生表：student
老師表：teacher
‘‘‘
mysql> create database sqlexam;
Query OK, 1 row affected (0.01 sec)
mysql> use sqlexam
Database changed
mysql>
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: 0
mysql> 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‘, ‘體育‘, ‘3‘), (‘4‘, ‘美術‘, ‘2‘);
Query OK, 4 rows affected (0.01 sec)
Records: 4 Duplicates: 0 Warnings: 0
mysql> 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: 0
mysql> 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‘, ‘鋼蛋‘), (‘3‘, ‘男‘, ‘1‘, ‘張三‘), (‘4‘, ‘男‘, ‘1‘, ‘張一‘), (‘5‘, ‘女‘, ‘1‘, ‘張二‘), (‘6‘, ‘男‘, ‘1‘, ‘張四‘), (‘7‘, ‘女‘, ‘2‘, ‘鐵錘‘), (‘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‘, ‘劉三‘), (‘14‘, ‘男‘, ‘3‘, ‘劉 一‘), (‘15‘, ‘女‘, ‘3‘, ‘劉二‘), (‘16‘, ‘男‘, ‘3‘, ‘劉四‘);
Query OK, 16 rows affected (0.01 sec)
Records: 16 Duplicates: 0 Warnings: 0
mysql> 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‘, ‘張磊老師‘), (‘2‘, ‘李平老師‘), (‘3‘, ‘劉海燕老師‘), (‘4‘, ‘朱雲海老師‘), (‘5‘, ‘李傑老師‘);
Query OK, 5 rows affected (0.00 sec)
Records: 5 Duplicates: 0 Warnings: 0
mysql> 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、查詢所有的課程的名稱以及對應的任課老師姓名
mysql> SELECT
-> course.cname,
-> teacher.tname
-> FROM
-> course
-> INNER JOIN teacher ON course.teacher_id = teacher.tid;
+--------+-----------------+
| cname | tname |
+--------+-----------------+
| 生物 | 張磊老師 |
| 物理 | 李平老師 |
| 美術 | 李平老師 |
| 體育 | 劉海燕老師 |
+--------+-----------------+
4 rows in set (0.01 sec)
# 2、查詢學生表中男女生各有多少人
mysql> SELECT
-> gender 性別,
-> count(1) 人數
-> FROM
-> student
-> GROUP BY
-> gender;
+--------+--------+
| 性別 | 人數 |
+--------+--------+
| 女 | 6 |
| 男 | 10 |
+--------+--------+
2 rows in set (0.00 sec)
# 3、查詢物理成績等於100的學生的姓名
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 |
+--------+
| 張四 |
| 鐵錘 |
| 李三 |
+--------+
3 rows in set (0.00 sec)
# 4、查詢平均成績大於八十分的同學的姓名和平均成績
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 |
+--------+---------+
| 張三 | 82.2500 |
| 劉三 | 87.0000 |
+--------+---------+
2 rows in set (0.00 sec)
# 5、查詢所有學生的學號，姓名，選課數，總成績
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 | 鋼蛋 | 3 | 175 |
| 3 | 張三 | 4 | 329 |
| 4 | 張一 | 4 | 257 |
| 5 | 張二 | 4 | 257 |
| 6 | 張四 | 4 | 276 |
| 7 | 鐵錘 | 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 | 劉三 | 1 | 87 |
| 14 | 劉一 | NULL | NULL |
| 15 | 劉二 | NULL | NULL |
| 16 | 劉四 | NULL | NULL |
+-----+--------+------------+-----------+
16 rows in set (0.00 sec)
# 6、 查詢姓李老師的個數
mysql> SELECT
-> count(tid)
-> FROM
-> teacher
-> WHERE
-> tname LIKE ‘李%‘;
+------------+
| count(tid) |
+------------+
| 2 |
+------------+
1 row in set (0.00 sec)
# 7、 查詢沒有報李平老師課的學生姓名
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 = ‘李平老師‘
-> )
-> );
+--------+
| sname |
+--------+
| 劉三 |
| 劉一 |
| 劉二 |
| 劉四 |
+--------+
4 rows in set (0.00 sec)
# 8、 查詢物理課程比生物課程高的學生的學號
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、 查詢沒有同時選修物理課程和體育課程的學生姓名
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 = ‘體育‘
-> )
-> GROUP BY
-> student_id
-> HAVING
-> COUNT(course_id) = 1
-> );
+--------+
| sname |
+--------+
| 理解 |
| 鋼蛋 |
| 劉三 |
+--------+
3 rows in set (0.00 sec)
# 10、查詢掛科超過兩門(包括兩門)的學生姓名和班級
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)
python之數據庫