MySQL 查询语句练习2

创建表

/*
Navicat MySQL Data Transfer

Source Server         : localhost_3306
Source Server Version : 50719
Source Host           : localhost:3306
Source Database       : oldbo

Target Server Type    : MYSQL
Target Server Version : 50719
File Encoding         : 65001

Date: 2017-07-26 15:46:16
*/

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) NOT NULL,
  PRIMARY KEY (`cid`)
) ENGINE=InnoDB AUTO_INCREMENT=5 DEFAULT CHARSET=utf8;

-- ----------------------------
-- Records of class
-- ----------------------------
INSERT INTO `class` VALUES ('', '三年二班');
INSERT INTO `class` VALUES ('', '三年三班');
INSERT INTO `class` VALUES ('', '一年二班');
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,
  `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;

-- ----------------------------
-- 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 ('', '', '', '');

-- ----------------------------
-- Table structure for student
-- ----------------------------
DROP TABLE IF EXISTS `student`;
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;

-- ----------------------------
-- 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');

-- ----------------------------
-- 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');
SET FOREIGN_KEY_CHECKS=1;

1、将所有的课程的名称以及对应的任课老师姓名打印出来，如下：

mysql> SELECT cname,tname FROM course LEFT JOIN teacher ON course.`teacher_id`=teacher.`tid`;
+--------+-----------------+
| cname | tname |
+--------+-----------------+
| 生物 | 张磊老师 |
| 物理 | 李平老师 |
| 体育 | 刘海燕老师 |
| 美术 | 李平老师 |
+--------+-----------------+
4 rows in set (0.00 sec)

　　

2、查询学生表中男女生各有多少人？ 如下：

mysql> SELECT gender,COUNT(sid) FROM student GROUP BY gender;
+--------+------------+
| gender | COUNT(sid) |
+--------+------------+
| 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？如下：

mysql> SELECT sname FROM student WHERE sid IN(SELECT student_id FROM score WHERE course_id=2 AND 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，如下：

mysql> SELECT sname AS '姓名',avgnum AS '平均分' FROM student INNER JOIN (SELECT student_id,AVG(num)AS avgnum FROM score GROUP BY student_id HAVING AVG(num)>80)AS id_avgnum ON student.`sid`=id_avgnum.student_id;
+--------+-----------+
| 姓名   | 平均分    |
+--------+-----------+
| 张三   |   82.2500 |
| 刘三   |   87.0000 |
+--------+-----------+
2 rows in set (0.00 sec)

mysql> SELECT sname,AVG(num) FROM student INNER JOIN score ON student.`sid`=score.`student_id` GROUP BY student_id HAVING AVG(num)>80;
+--------+----------+
| sname  | AVG(num) |
+--------+----------+
| 张三   |  82.2500 |
| 刘三   |  87.0000 |
+--------+----------+
2 rows in set (0.01 sec)

　　

5、查询所有学生的学号，姓名，选课数，总成绩

mysql> SELECT student.sid,sname,SUM(num),COUNT(course_id) FROM student INNER JOIN score ON student.`sid`=score.`student_id` GROUP BY student_id;
+-----+--------+----------+------------------+
| sid | sname | SUM(num) | COUNT(course_id) |
+-----+--------+----------+------------------+
| 1 | 理解 | 85 | 3 |
| 2 | 钢蛋 | 175 | 3 |
| 3 | 张三 | 329 | 4 |
| 4 | 张一 | 257 | 4 |
| 5 | 张二 | 257 | 4 |
| 6 | 张四 | 276 | 4 |
| 7 | 铁锤 | 264 | 4 |
| 8 | 李三 | 264 | 4 |
| 9 | 李一 | 268 | 4 |
| 10 | 李二 | 297 | 4 |
| 11 | 李四 | 297 | 4 |
| 12 | 如花 | 297 | 4 |
| 13 | 刘三 | 87 | 1 |
+-----+--------+----------+------------------+
13 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 sname FROM student WHERE sid NOT IN(SELECT student_id FROM score WHERE course_id IN(SELECT cid FROM course WHERE teacher_id=(SELECT tid FROM teacher WHERE 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

SELECT A.student_id,A.num,b.num FROM

(SELECT * FROM score WHERE course_id=(SELECT cid FROM course WHERE cname="物理"))as A

INNER JOIN

(SELECT * FROM score WHERE course_id=(SELECT cid FROM course WHERE cname="生物"))as B

ON
A.student_id=B.student_id

WHERE A.num>B.num

　　

9、查询没有同时选修物理课程和体育课程的学生姓名

SELECT sname FROM student WHERE sid NOT 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(sid)=2)

　　

10、查询挂科超过两门(包括两门)的学生姓名和班级

SELECT sname,caption FROM student LEFT JOIN class ON student.class_id=class.cid
where sid in (SELECT student_id FROM score WHERE num<60
GROUP BY student_id HAVING COUNT(sid)>1)

　　

11 、查询选修了所有课程的学生姓名

SELECT sname FROM student WHERE sid in (SELECT student_id FROM score

GROUP BY student_id HAVING COUNT(sid)!=(SELECT COUNT(cid) FROM course))

　　

12、查询李平老师教的课程的所有成绩记录

SELECT * FROM score WHERE course_id in (SELECT cid FROM course LEFT JOIN teacher ON teacher.tid=course.teacher_id
WHERE tname="李平老师")

13、查询全部学生都选修了的课程号和课程名
无

14、查询每门课程被选修的次数

mysql> SELECT course.cname,COUNT(score.course_id) FROM course INNER JOIN score ON course.cid=score.course_id GROUP BY score.course_id;
+--------+------------------------+
| cname | COUNT(score.course_id) |
+--------+------------------------+
| 生物 | 12 |
| 物理 | 11 |
| 体育 | 12 |
| 美术 | 12 |
+--------+------------------------+
4 rows in set (0.00 sec)

　　

15、查询之选修了一门课程的学生姓名和学号

mysql> SELECT student_id,student.sname,COUNT(course_id) FROM student INNER JOIN score ON student.`sid`=score.`student_id` GROUP BY student_id HAVING COUNT(course_id)=1;
+------------+--------+------------------+
| student_id | sname | COUNT(course_id) |
+------------+--------+------------------+
| 13 | 刘三 | 1 |
+------------+--------+------------------+
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,AVG(num) FROM student INNER JOIN score ON student.`sid`=score.`student_id` GROUP BY student_id HAVING AVG(num)>85;
+--------+----------+
| 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 student.`sname`,A.num FROM student INNER JOIN (SELECT student_id,num FROM score WHERE num<60 AND course_id=(SELECT cid FROM course WHERE cname='生物'))AS A ON student.sid=A.student_id;
+--------+-----+
| sname | 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 INNER JOIN (SELECT student_id,SUM(num) FROM (SELECT * FROM score WHERE course_id IN(SELECT cid FROM course WHERE teacher_id=(SELECT tid FROM teacher WHERE tname='李平老师')))AS aa GROUP BY student_id DESC LIMIT 1)AS bb ON student.sid=bb.student_id;
+--------+
| sname |
+--------+
| 如花 |
+--------+
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(答案非准确)

mysql> SELECT student.`sname`,ee.course_id,ee.num FROM student INNER JOIN
-> (SELECT * FROM (SELECT student_id,course_id,num FROM score WHERE course_id=1 ORDER BY num DESC LIMIT 2)AS aa
-> UNION ALL SELECT * FROM (SELECT student_id,course_id,num FROM score WHERE course_id=2 ORDER BY num DESC LIMIT 2)AS bb
-> UNION ALL SELECT * FROM (SELECT student_id,course_id,num FROM score WHERE course_id=3 ORDER BY num DESC LIMIT 2)AS cc
-> UNION ALL SELECT * FROM (SELECT student_id,course_id,num FROM score WHERE course_id=4 ORDER BY num DESC LIMIT 2)AS dd)AS ee
-> ON student.sid=ee.student_id;
+--------+-----------+-----+
| sname | course_id | num |
+--------+-----------+-----+
| 李一 | 1 | 91 |
| 如花 | 1 | 90 |
| 张四 | 2 | 100 |
| 铁锤 | 2 | 100 |
| 张三 | 3 | 87 |
| 刘三 | 3 | 87 |
| 张一 | 4 | 100 |
| 张二 | 4 | 100 |
+--------+-----------+-----+
8 rows in set (0.01 sec)