mysql作业记录

MySQL

一、表关系

请创建如下表，并创建相关约束

C:\Users\Administrator>mysql -uroot -p
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Your MySQL connection id is 1
Server version: 5.6.39 MySQL Community Server (GPL)

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Type ‘help;‘ or ‘\h‘ for help. Type ‘\c‘ to clear the current input statement.

mysql> create database db charset utf8;
Query OK, 1 row affected (0.01 sec)

mysql> use db;
Database changed
mysql> create table class_grade(
    -> gid int primary key auto_increment,
    -> gname varchar(16) not null unique);
Query OK, 0 rows affected (1.14 sec)

mysql> create table class(
    -> cid int primary key auto_increment,
    -> caption varchar(16) not null,
    -> grade_id int not null,
    -> foreign key(grade_id) references class_grade(gid));
Query OK, 0 rows affected (0.95 sec)

mysql> create table student(
    -> sid int primary key auto_increment,
    -> sname varchar(16) not null,
    -> sex enum(‘女‘,‘男‘),
    -> class_id int not null,
    -> foreign key(class_id) references class(cid));
Query OK, 0 rows affected (0.64 sec)

mysql> create table teacher(
    -> tid int primary key auto_increment,
    -> tname varchar(16) not null);
Query OK, 0 rows affected (0.59 sec)

mysql> create table course(
    -> cid int primary key auto_increment,
    -> cname varchar(16) not null,
    -> teacher_id int not null,
    -> foreign key(teacher_id) references teacher(tid));
Query OK, 0 rows affected (0.53 sec)

mysql> create table score(
    -> sid int primary key auto_increment,
    -> student_id int not null,
    -> course_id int not null,
    -> score int not null,
    -> primary key(student_id,course_id),
    -> foreign key(student_id) references student(sid)
    -> on delete cascade
    -> on update cascade,
    -> foreign key(course_id) references course(cid)
    -> on delete cascade
    -> on update cascade);
ERROR 1068 (42000): Multiple primary key defined
mysql> create table score(
    ->     sid int not null unique auto_increment,
    ->     student_id int not null,
    ->     course_id int not null,
    ->     score int not null,
    ->     primary key(student_id,course_id),
    ->     foreign key(student_id) references student(sid)
    ->     on delete cascade
    ->     on update cascade,
    ->     foreign key(course_id) references course(cid)
    ->     on delete cascade
    ->     on update cascade
    -> );
Query OK, 0 rows affected (1.11 sec)

mysql> create teach2cls(
    -> tcid int not null unique auto_increment,
    -> tid int not null,
    -> cid int not null,
    -> primary key(tid,cid),
    -> foreign key(tid) references teacher(tid)
    -> on delete cascade
    -> on update cascade,
    -> foreign key(cid) references class(cid)
    -> on delete cascade
    -> on update cascade);
ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near ‘teach2cls(
tcid int not null unique auto_increment,
tid int not null,
cid int no‘ at line 1
mysql> create table teach2cls(
    ->     tcid int not null unique auto_increment,
    ->     tid int not null,
    ->     cid int not null,
    ->     primary key(tid,cid),
    ->     foreign key(tid) references teacher(tid)
    ->     on delete cascade
    ->     on update cascade,
    ->     foreign key(cid) references class(cid)
    ->     on delete cascade
    ->     on update cascade
    -> );
Query OK, 0 rows affected (0.87 sec)

mysql>

mysql> desc teach2cls;
+-------+---------+------+-----+---------+----------------+
| Field | Type    | Null | Key | Default | Extra          |
+-------+---------+------+-----+---------+----------------+
| tcid  | int(11) | NO   | UNI | NULL    | auto_increment |
| tid   | int(11) | NO   | PRI | NULL    |                |
| cid   | int(11) | NO   | PRI | NULL    |                |
+-------+---------+------+-----+---------+----------------+
3 rows in set (0.10 sec)

mysql> desc score;
+------------+---------+------+-----+---------+----------------+
| Field      | Type    | Null | Key | Default | Extra          |
+------------+---------+------+-----+---------+----------------+
| sid        | int(11) | NO   | UNI | NULL    | auto_increment |
| student_id | int(11) | NO   | PRI | NULL    |                |
| course_id  | int(11) | NO   | PRI | NULL    |                |
| score      | int(11) | NO   |     | NULL    |                |
+------------+---------+------+-----+---------+----------------+
4 rows in set (0.01 sec)

mysql> desc course;
+------------+-------------+------+-----+---------+----------------+
| Field      | Type        | Null | Key | Default | Extra          |
+------------+-------------+------+-----+---------+----------------+
| cid        | int(11)     | NO   | PRI | NULL    | auto_increment |
| cname      | varchar(16) | NO   |     | NULL    |                |
| teacher_id | int(11)     | NO   | MUL | NULL    |                |
+------------+-------------+------+-----+---------+----------------+
3 rows in set (0.02 sec)

mysql> desc teacher;
+-------+-------------+------+-----+---------+----------------+
| Field | Type        | Null | Key | Default | Extra          |
+-------+-------------+------+-----+---------+----------------+
| tid   | int(11)     | NO   | PRI | NULL    | auto_increment |
| tname | varchar(16) | NO   |     | NULL    |                |
+-------+-------------+------+-----+---------+----------------+
2 rows in set (0.01 sec)

mysql> desc student;
+----------+-------------------+------+-----+---------+----------------+
| Field    | Type              | Null | Key | Default | Extra          |
+----------+-------------------+------+-----+---------+----------------+
| sid      | int(11)           | NO   | PRI | NULL    | auto_increment |
| sname    | varchar(16)       | NO   |     | NULL    |                |
| sex      | enum(‘女‘,‘男‘)   | YES  |     | NULL    |                |
| class_id | int(11)           | NO   | MUL | NULL    |                |
+----------+-------------------+------+-----+---------+----------------+
4 rows in set (0.08 sec)

mysql> desc class;
+----------+-------------+------+-----+---------+----------------+
| Field    | Type        | Null | Key | Default | Extra          |
+----------+-------------+------+-----+---------+----------------+
| cid      | int(11)     | NO   | PRI | NULL    | auto_increment |
| caption  | varchar(16) | NO   |     | NULL    |                |
| grade_id | int(11)     | NO   | MUL | NULL    |                |
+----------+-------------+------+-----+---------+----------------+
3 rows in set (0.01 sec)

mysql> desc class_grade;
+-------+-------------+------+-----+---------+----------------+
| Field | Type        | Null | Key | Default | Extra          |
+-------+-------------+------+-----+---------+----------------+
| gid   | int(11)     | NO   | PRI | NULL    | auto_increment |
| gname | varchar(16) | NO   | UNI | NULL    |                |
+-------+-------------+------+-----+---------+----------------+
2 rows in set (0.01 sec)

二、插入数据

mysql> select * from class;
+-----+-----------------+----------+
| cid | caption         | grade_id |
+-----+-----------------+----------+
|   1 | 一年级一班      |        1 |
|   2 | 一年级二班      |        1 |
|   3 | 一年级三班      |        1 |
|   4 | 二年级一班      |        2 |
|   5 | 二年级二班      |        2 |
|   6 | 二年级三班      |        2 |
|   7 | 三年级一班      |        3 |
|   8 | 三年级二班      |        3 |
|   9 | 三年级三班      |        3 |
+-----+-----------------+----------+
9 rows in set (0.00 sec)

mysql> select * from class_grade;
+-----+-----------+
| gid | gname     |
+-----+-----------+
|   1 | 一年级    |
|   3 | 三年级    |
|   2 | 二年级    |
|   4 | 四年级    |
+-----+-----------+
4 rows in set (0.00 sec)

mysql> select * from course;
+-----+--------+------------+
| cid | cname  | teacher_id |
+-----+--------+------------+
|   1 | 生物   |          1 |
|   2 | 体育   |          1 |
|   3 | 物理   |          2 |
|   4 | 化学   |          3 |
|   5 | 英语   |          3 |
|   6 | python |          4 |
|   7 | linux  |          5 |
+-----+--------+------------+
7 rows in set (0.00 sec)

mysql> select * from student;
+-----+-----------+------+----------+
| sid | sname     | sex  | class_id |
+-----+-----------+------+----------+
|   1 | 乔丹      | 女   |        1 |
|   2 | 艾弗森    | 女   |        1 |
|   3 | 科比      | 男   |        2 |
|   4 | alex      | 女   |        2 |
|   5 | egon      | 男   |        3 |
|   6 | egon2     | 女   |        3 |
|   7 | kris      | 男   |        4 |
|   8 | wxx       | 女   |        5 |
|   9 | 杜拉拉    | 女   |        6 |
|  10 | 姗姗      | 女   |        7 |
|  11 | 丹丹      | 男   |        8 |
|  12 | simith    | 男   |        9 |
+-----+-----------+------+----------+
12 rows in set (0.00 sec)

mysql> select * from teacher;
+-----+-----------+
| tid | tname     |
+-----+-----------+
|   1 | 张三      |
|   2 | 李四      |
|   3 | 王五      |
|   4 | 老男孩    |
|   5 | 小女孩    |
+-----+-----------+
5 rows in set (0.00 sec)

mysql> select * from score;
+-----+------------+-----------+-------+
| sid | student_id | course_id | score |
+-----+------------+-----------+-------+
|   1 |          1 |         1 |    60 |
|   2 |          1 |         2 |    59 |
|   3 |          2 |         2 |    99 |
|   4 |          3 |         3 |    88 |
|   5 |          3 |         4 |    76 |
|   6 |          4 |         5 |    34 |
|   7 |          5 |         6 |    68 |
|   8 |          6 |         6 |    93 |
|   9 |          7 |         7 |    77 |
|  10 |          8 |         6 |    86 |
|  11 |          9 |         3 |    90 |
|  12 |         10 |         4 |   100 |
|  13 |         11 |         5 |    52 |
|  14 |         12 |         7 |    27 |
+-----+------------+-----------+-------+
14 rows in set (0.00 sec)

mysql> select * from teach2cls;
+------+-----+-----+
| tcid | tid | cid |
+------+-----+-----+
|    1 |   1 |   1 |
|    2 |   1 |   2 |
|    3 |   2 |   1 |
|    4 |   3 |   2 |
|    5 |   4 |   3 |
|    6 |   4 |   4 |
|    7 |   5 |   6 |
|    8 |   5 |   5 |
|    9 |   3 |   7 |
|   10 |   2 |   8 |
|   11 |   4 |   9 |
+------+-----+-----+
11 rows in set (0.00 sec)

三、操作表

1、自行创建测试数据；见上

2、查询学生总人数；

mysql> select count(sid) as count_student from student;
+---------------+
| count_student |
+---------------+
|            12 |
+---------------+
1 row in set (0.08 sec)

3、查询“生物”课程和“物理”课程成绩都及格的学生id和姓名；

mysql> select sid,sname from student
    -> where sid in(
    -> SELECT score.student_id from score inner join course on score.course_id = course.cid
    -> where course.cname in (‘生物‘, ‘物理‘) and score.score > 60
    -> );
+-----+-----------+
| sid | sname     |
+-----+-----------+
|   1 | 乔丹      |
|   3 | 科比      |
|   9 | 杜拉拉    |
+-----+-----------+

4、查询每个年级的班级数，取出班级数最多的前三个年级；

mysql> select class_grade.gname from class_grade inner join(
    -> select grade_id,count(cid) as count_cid from class
    -> group by grade_id
    -> order by count_cid desc
    -> limit 3)
    -> as t1
    -> on class_grade.gid = t1.grade_id;
+-----------+
| gname     |
+-----------+
| 一年级    |
| 三年级    |
| 二年级    |
+-----------+
3 rows in set (0.00 sec)

5、查询平均成绩最高和最低的学生的id和姓名以及平均成绩；

mysql> select student.sid,student.sname,t1.avg_score from student
    -> inner join(select student_id,avg(score) as avg_score from score
    -> group by student_id
    -> having avg(score) in ((
    -> select avg(score) as max_avg_score from score
    -> group by student_id
    -> order by avg(score) desc
    -> limit 1),(
    -> select avg(score) as min_avg_score from score
    -> group by student_id
    -> order by avg(score) asc
    -> limit 1)
    -> )) as t1
    -> on student.sid = t1.student_id;
+-----+--------+-----------+
| sid | sname  | avg_score |
+-----+--------+-----------+
|  10 | 姗姗   |  100.0000 |
|  12 | simith |   27.0000 |
+-----+--------+-----------+
2 rows in set (0.05 sec)

6、查询每个年级的学生人数；

mysql> select student.sid, class.grade_id from student,class
    -> where student.class_id = class.cid;
+-----+----------+
| sid | grade_id |
+-----+----------+
|   1 |        1 |
|   2 |        1 |
|   3 |        1 |
|   4 |        1 |
|   5 |        1 |
|   6 |        1 |
|   7 |        2 |
|   8 |        2 |
|   9 |        2 |
|  10 |        3 |
|  11 |        3 |
|  12 |        3 |
+-----+----------+
12 rows in set (0.00 sec)

mysql> select t1.grade_id, count(t1.sid) as student_count from
    -> (select student.sid, class.grade_id from student,class
    -> where student.class_id = class.cid)as t1
    -> group by t1.grade_id;
+----------+---------------+
| grade_id | student_count |
+----------+---------------+
|        1 |             6 |
|        2 |             3 |
|        3 |             3 |
+----------+---------------+
3 rows in set (0.00 sec)

7、查询每位学生的学号，姓名，选课数，平均成绩；

mysql> select student_id, count(course_id) as count_course,
    -> avg(score) as avg_score from score
    -> group by student_id;
+------------+--------------+-----------+
| student_id | count_course | avg_score |
+------------+--------------+-----------+
|          1 |            3 |   65.0000 |
|          2 |            1 |   99.0000 |
|          3 |            1 |   88.0000 |
|          4 |            1 |   34.0000 |
|          5 |            1 |   68.0000 |
|          6 |            1 |   93.0000 |
|          7 |            1 |   77.0000 |
|          8 |            1 |   86.0000 |
|          9 |            1 |   90.0000 |
|         10 |            1 |  100.0000 |
|         11 |            1 |   52.0000 |
|         12 |            1 |   27.0000 |
+------------+--------------+-----------+
12 rows in set (0.00 sec)

mysql> select student.sid, student.sname,t1.count_course, t1.avg_score from student left join(
    -> select student_id, count(course_id) as count_course,
    -> avg(score) as avg_score from score
    -> group by student_id)
    -> as t1
    -> on student.sid = t1.student_id;
+-----+-----------+--------------+-----------+
| sid | sname     | count_course | avg_score |
+-----+-----------+--------------+-----------+
|   1 | 乔丹      |            3 |   65.0000 |
|   2 | 艾弗森    |            1 |   99.0000 |
|   3 | 科比      |            1 |   88.0000 |
|   4 | alex      |            1 |   34.0000 |
|   5 | egon      |            1 |   68.0000 |
|   6 | egon2     |            1 |   93.0000 |
|   7 | kris      |            1 |   77.0000 |
|   8 | wxx       |            1 |   86.0000 |
|   9 | 杜拉拉    |            1 |   90.0000 |
|  10 | 姗姗      |            1 |  100.0000 |
|  11 | 丹丹      |            1 |   52.0000 |
|  12 | simith    |            1 |   27.0000 |
+-----+-----------+--------------+-----------+
12 rows in set (0.00 sec)

8、查询学生编号为“2”的学生的姓名、该学生成绩最高的课程名、成绩最低的课程名及分数；

mysql> select student_id, course_id, score from score
    -> where student_id = 2 and score in ((
    -> select max(score) from score where student_id = 2),(
    -> select min(score) from score where student_id = 2));
+------------+-----------+-------+
| student_id | course_id | score |
+------------+-----------+-------+
|          2 |         2 |    99 |
+------------+-----------+-------+
1 row in set (0.03 sec)

mysql> select student.sname,course.cname,t1.score from(
    -> select student_id, course_id, score from score
    -> where student_id = 2 and score in ((
    -> select max(score) from score where student_id = 2),(
    -> select min(score) from score where student_id = 2))
    -> )as t1 inner join student on t1.student_id = student.sid
    -> inner join course on t1.course_id = course.cid;
+-----------+--------+-------+
| sname     | cname  | score |
+-----------+--------+-------+
| 艾弗森    | 体育   |    99 |
+-----------+--------+-------+
1 row in set (0.00 sec)

9、查询姓“李”的老师的个数和所带班级数；

mysql> select tid, count(cid) as count_cid from teach2cls
    -> where tid in (
    -> select tid from teacher
    -> where tname like ‘李%‘)
    -> group by tid;
+-----+-----------+
| tid | count_cid |
+-----+-----------+
|   2 |         2 |
+-----+-----------+
1 row in set (0.00 sec)

mysql> select teacher.tid, teacher.tname,t1.count_cid from teacher left join(
    -> select tid, count(cid) as count_cid from teach2cls
    -> where tid in (
    -> select tid from teacher
    -> where tname like ‘李%‘)
    -> group by tid)as t1
    -> on teacher.tid = t1.tid
    -> where teacher.tname like ‘李%‘;
+-----+--------+-----------+
| tid | tname  | count_cid |
+-----+--------+-----------+
|   2 | 李四   |         2 |
+-----+--------+-----------+
1 row in set (0.00 sec)

10、查询班级数小于5的年级id和年级名；

mysql> select gid, gname from class_grade
    -> where gid in(
    -> select grade_id from class
    -> group by grade_id
    -> having count(class.grade_id) < 5
    -> );
+-----+-----------+
| gid | gname     |
+-----+-----------+
|   1 | 一年级    |
|   3 | 三年级    |
|   2 | 二年级    |
+-----+-----------+
3 rows in set (0.00 sec)

11、查询班级信息，包括班级id、班级名称、年级、年级级别(12为低年级，34为中年级，56为高年级)，示例结果如下；

mysql> select class.cid, class.caption, class_grade.gname,case
    -> when class_grade.gid between 1 and 2 then ‘低‘
    -> when class_grade.gid between 3 and 4 then ‘中‘
    -> when class_grade.gid between 5 and 6 then ‘高‘
    -> else 0
    -> end as ‘年级级别‘ from class, class_grade
    -> where class.grade_id = class_grade.gid;
+-----+-----------------+-----------+--------------+
| cid | caption         | gname     | 年级级别     |
+-----+-----------------+-----------+--------------+
|   1 | 一年级一班      | 一年级    | 低           |
|   2 | 一年级二班      | 一年级    | 低           |
|   3 | 一年级三班      | 一年级    | 低           |
|   7 | 三年级一班      | 三年级    | 中           |
|   8 | 三年级二班      | 三年级    | 中           |
|   9 | 三年级三班      | 三年级    | 中           |
|   4 | 二年级一班      | 二年级    | 低           |
|   5 | 二年级二班      | 二年级    | 低           |
|   6 | 二年级三班      | 二年级    | 低           |
+-----+-----------------+-----------+--------------+
9 rows in set (0.00 sec)

12、查询学过“张三”老师2门课以上的同学的学号、姓名；

mysql> select student_id from score
    -> where course_id in (
    -> select course.cid from teacher, course
    -> where teacher.tid = course.teacher_id and teacher.tname = ‘张三‘)
    -> group by student_id
    -> having count(course_id) > 2;
Empty set (0.00 sec)

mysql> select sid,sname from student
    -> where sid in(
    ->  select student_id from score
    ->  where course_id in (
    ->  select course.cid from teacher, course
    ->  where teacher.tid = course.teacher_id and teacher.tname = ‘张三‘)
    ->  group by student_id
    -> having count(course_id) > 2
    -> );
Empty set (0.00 sec)

13、查询教授课程超过2门的老师的id和姓名；

mysql> select tid, tname from teacher
    -> where tid in (
    -> select teacher_id from course
    -> group by teacher_id
    -> having count(cid) >= 2
    -> );
+-----+--------+
| tid | tname  |
+-----+--------+
|   1 | 张三   |
|   3 | 王五   |
+-----+--------+
2 rows in set (0.00 sec)

14、查询学过编号“1”课程和编号“2”课程的同学的学号、姓名；

mysql> select distinct student_id from score
    -> where course_id in (1, 2);
+------------+
| student_id |
+------------+
|          1 |
|          2 |
+------------+
2 rows in set (0.05 sec)

mysql> select sid, sname from student
    -> where sid in(
    ->  select distinct student_id from score
    ->  where course_id in (1, 2)
    ->  );
+-----+-----------+
| sid | sname     |
+-----+-----------+
|   1 | 乔丹      |
|   2 | 艾弗森    |
+-----+-----------+
2 rows in set (0.23 sec)

15、查询没有带过高年级的老师id和姓名；

mysql> select tid,tname from teacher
    -> where tid not in (
    -> select tid from teach2cls
    -> where cid in (
    -> select t1.cid from(
    -> select class.cid,class.caption,class_grade.gname,
    -> case when class_grade.gid between 1 and 2 then ‘低‘
    -> when class_grade.gid between 3 and 4 then ‘中‘
    -> when class_grade.gid between 5 and 6 then ‘高‘ else 0 end as grade_layer
    -> from class,class_grade
    -> where class.grade_id = class_grade.gid)
    -> as t1
    -> where t1.grade_layer = ‘高‘)
    -> );
+-----+-----------+
| tid | tname     |
+-----+-----------+
|   1 | 张三      |
|   2 | 李四      |
|   3 | 王五      |
|   4 | 老男孩    |
|   5 | 小女孩    |
+-----+-----------+
5 rows in set (0.06 sec)

16、查询学过“张三”老师所教的所有课的同学的学号、姓名；

mysql> select student_id from score
    -> where course_id in (
    -> select cid from course
    -> inner join teacher on teacher.tid = course.teacher_id
    -> where teacher.tname = ‘张三‘);
+------------+
| student_id |
+------------+
|          1 |
|          1 |
|          2 |
+------------+
3 rows in set (0.00 sec)

mysql> select sid, sname from student
    -> where sid in (
    -> select student_id from score
    -> where course_id in (
    -> select cid from course
    -> inner join teacher on teacher.tid = course.teacher_id
    -> where teacher.tname = ‘张三‘)
    -> );
+-----+-----------+
| sid | sname     |
+-----+-----------+
|   1 | 乔丹      |
|   2 | 艾弗森    |
+-----+-----------+
2 rows in set (0.00 sec)

17、查询带过超过2个班级的老师的id和姓名；

mysql> select tid, tname from teacher
    -> where tid in (
    -> select tid from teach2cls
    -> group by tid
    -> having count(cid) > 2
    -> );
+-----+-----------+
| tid | tname     |
+-----+-----------+
|   4 | 老男孩    |
+-----+-----------+
1 row in set (0.00 sec)

18、查询课程编号“2”的成绩比课程编号“1”课程低的所有同学的学号、姓名；

mysql> select t1.student_id from (
    -> select student_id, score from score
    -> where course_id = 2
    -> group by student_id)
    -> as t1,(
    -> select student_id, score from score
    -> where course_id = 1
    -> group by student_id)
    -> as t2
    -> where t1.student_id = t2.student_id
    -> and t1.score < t2.score ;
+------------+
| student_id |
+------------+
|          1 |
+------------+
1 row in set (0.00 sec)

mysql> select sid, sname from student
    -> where sid in (
    -> select t1.student_id from (
    -> select student_id, score from score
    -> where course_id = 2
    -> group by student_id)
    -> as t1,(
    -> select student_id, score from score
    -> where course_id = 1
    -> group by student_id)
    -> as t2
    -> where t1.student_id = t2.student_id
    -> and t1.score < t2.score
    -> );
+-----+--------+
| sid | sname  |
+-----+--------+
|   1 | 乔丹   |
+-----+--------+
1 row in set (0.00 sec)

19、查询所带班级数最多的老师id和姓名；

mysql> select tid from teach2cls
    -> group by tid
    -> having count(cid) = (
    -> select count(cid) from teach2cls
    -> group by tid
    -> order by count(cid) desc limit 1);
+-----+
| tid |
+-----+
|   4 |
+-----+
1 row in set (0.00 sec)

mysql> select tid, tname from teacher
    -> where tid in (
    -> select tid from teach2cls
    -> group by tid
    -> having count(cid) = (
    -> select count(cid) from teach2cls
    -> group by tid
    -> order by count(cid) desc limit 1)
    -> );
+-----+-----------+
| tid | tname     |
+-----+-----------+
|   4 | 老男孩    |
+-----+-----------+
1 row in set (0.00 sec)

mysql>

20、查询有课程成绩小于60分的同学的学号、姓名；

mysql> select sid, sname from student
    -> where sid in (
    -> select distinct student_id from score
    -> where score < 60);
+-----+--------+
| sid | sname  |
+-----+--------+
|   1 | 乔丹   |
|   4 | alex   |
|  11 | 丹丹   |
|  12 | simith |
+-----+--------+
4 rows in set (0.00 sec)

21、查询没有学全所有课的同学的学号、姓名；

mysql> select student_id from score
    -> group by student_id
    -> having count(course_id) = (
    -> select count(cid) from course);
Empty set (0.00 sec)

mysql> select sid, sname from student
    -> where sid not in (
    -> select student_id from score
    -> group by student_id
    -> having count(course_id) = (
    -> select count(cid) from course)
    -> );
+-----+-----------+
| sid | sname     |
+-----+-----------+
|   1 | 乔丹      |
|   2 | 艾弗森    |
|   3 | 科比      |
|   4 | alex      |
|   5 | egon      |
|   6 | egon2     |
|   7 | kris      |
|   8 | wxx       |
|   9 | 杜拉拉    |
|  10 | 姗姗      |
|  11 | 丹丹      |
|  12 | simith    |
+-----+-----------+
12 rows in set (0.00 sec)

22、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 student_id from score
where course_id in (
select course_id from score
where student_id = 1)
group by student_id
);

23、查询至少学过学号为“1”同学所选课程中任意一门课的其他同学学号和姓名；

mysql> select sid,sname from student
    -> where sid in (
    -> select student_id from score
    -> where course_id in (
    -> SELECT course_id from score
    -> where student_id = 1)
    -> group by student_id )
    -> and sid != 1;
+-----+-----------+
| sid | sname     |
+-----+-----------+
|   2 | 艾弗森    |
|   3 | 科比      |
|   9 | 杜拉拉    |
+-----+-----------+
3 rows in set (0.00 sec)

24、查询和“2”号同学学习的课程完全相同的其他同学的学号和姓名；

mysql> select sid,sname from student
    -> where sid in (
    -> select score.student_id from score,(
    -> select course_id from score
    -> where student_id = 2) as t1
    -> where score.course_id = t1.course_id and score.student_id != 2
    -> group by score.student_id
    -> having count(score.course_id) = (select count(course_id) from score
    -> where student_id = 2)
    -> );
+-----+--------+
| sid | sname  |
+-----+--------+
|   1 | 乔丹   |
+-----+--------+
1 row in set (0.00 sec)

25、删除学习“张三”老师课的score表记录；

mysql> delete from score
    -> where course_id in (
    -> select course.cid from course,teacher
    -> where course.teacher_id = teacher.tid and teacher.tname = ‘张三‘
    -> );
Query OK, 0 rows affected (0.17 sec)

mysql> select * from score;
+-----+------------+-----------+-------+
| sid | student_id | course_id | score |
+-----+------------+-----------+-------+
|   5 |          1 |         3 |    76 |
|   4 |          3 |         3 |    88 |
|   6 |          4 |         5 |    34 |
|   7 |          5 |         6 |    68 |
|   8 |          6 |         6 |    93 |
|   9 |          7 |         7 |    77 |
|  10 |          8 |         6 |    86 |
|  11 |          9 |         3 |    90 |
|  12 |         10 |         4 |   100 |
|  13 |         11 |         5 |    52 |
|  14 |         12 |         7 |    27 |
+-----+------------+-----------+-------+
11 rows in set (0.00 sec)

26、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“2”课程的同学学号；②插入“2”号课程的平均成绩；

mysql>  select sid from student
    ->  where sid not in (
    ->  select student_id from score where course_id = 2);
+-----+
| sid |
+-----+
|   1 |
|   2 |
|   3 |
|   4 |
|   5 |
|   6 |
|   7 |
|   8 |
|   9 |
|  10 |
|  11 |
+-----+
11 rows in set (0.00 sec)

mysql> select avg(score) as avg_score from score
    -> where course_id=2;
+-----------+
| avg_score |
+-----------+
|   27.0000 |
+-----------+
1 row in set (0.00 sec)
mysql> insert into score(student_id,course_id,score)
    -> select t1.sid,2,t2.avg_score from (
    -> select sid from student
    -> where sid not in (
    -> select student_id from score where course_id = 2)
    -> )as t1,(
    -> select avg(score) as avg_score from score
    -> where course_id=2)
    -> as t2;
Query OK, 0 rows affected (0.00 sec)
Records: 0  Duplicates: 0  Warnings: 0
mysql> select * from score;
+-----+------------+-----------+-------+
| sid | student_id | course_id | score |
+-----+------------+-----------+-------+
|  15 |          1 |         2 |    27 |
|   5 |          1 |         3 |    76 |
|  16 |          2 |         2 |    27 |
|  17 |          3 |         2 |    27 |
|   4 |          3 |         3 |    88 |
|  18 |          4 |         2 |    27 |
|   6 |          4 |         5 |    34 |
|  19 |          5 |         2 |    27 |
|   7 |          5 |         6 |    68 |
|  20 |          6 |         2 |    27 |
|   8 |          6 |         6 |    93 |
|  21 |          7 |         2 |    27 |
|   9 |          7 |         7 |    77 |
|  22 |          8 |         2 |    27 |
|  10 |          8 |         6 |    86 |
|  23 |          9 |         2 |    27 |
|  11 |          9 |         3 |    90 |
|  24 |         10 |         2 |    27 |
|  12 |         10 |         4 |   100 |
|  25 |         11 |         2 |    27 |
|  13 |         11 |         5 |    52 |
|  14 |         12 |         2 |    27 |
+-----+------------+-----------+-------+
22 rows in set (0.00 sec)

27、按平均成绩从低到高显示所有学生的“语文”、“数学”、“英语”三门的课程成绩，按如下形式显示： 学生ID,语文,数学,英语,有效课程数,有效平均分；

mysql> select concat("学生ID:  ",t1.sid," ", "课程ID:  ",t2.course_id," ","平均成绩:  ",avg(t2.score)) from student
    -> as t1
    -> RIGHT JOIN score as t2
    -> on t1.sid = t2.student_id
    -> GROUP BY student_id;
+--------------------------------------------------------------------------------------------------+
| concat("学生ID:  ",t1.sid," ", "课程ID:  ",t2.course_id," ","平均成绩:  ",avg(t2.score))         |
+--------------------------------------------------------------------------------------------------+
| 学生ID:  1 课程ID:  2 平均成绩:  51.5000                                                         |
| 学生ID:  2 课程ID:  2 平均成绩:  27.0000                                                         |
| 学生ID:  3 课程ID:  2 平均成绩:  57.5000                                                         |
| 学生ID:  4 课程ID:  2 平均成绩:  30.5000                                                         |
| 学生ID:  5 课程ID:  2 平均成绩:  47.5000                                                         |
| 学生ID:  6 课程ID:  2 平均成绩:  60.0000                                                         |
| 学生ID:  7 课程ID:  2 平均成绩:  52.0000                                                         |
| 学生ID:  8 课程ID:  2 平均成绩:  56.5000                                                         |
| 学生ID:  9 课程ID:  2 平均成绩:  58.5000                                                         |
| 学生ID:  10 课程ID:  2 平均成绩:  63.5000                                                        |
| 学生ID:  11 课程ID:  2 平均成绩:  39.5000                                                        |
| 学生ID:  12 课程ID:  2 平均成绩:  27.0000                                                        |
+--------------------------------------------------------------------------------------------------+
12 rows in set (0.00 sec)

28、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；

mysql> select course.cid, max(score.score) as max_score, min(score.score) as min_score from course
    -> left join score on course.cid = score.course_id
    -> group by score.course_id;
+-----+-----------+-----------+
| cid | max_score | min_score |
+-----+-----------+-----------+
|   1 |      NULL |      NULL |
|   2 |        27 |        27 |
|   3 |        90 |        76 |
|   4 |       100 |       100 |
|   5 |        52 |        34 |
|   6 |        93 |        68 |
|   7 |        77 |        77 |
+-----+-----------+-----------+
7 rows in set (0.00 sec)

29、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；

mysql> select course_id, avg(score) as avg_score,
    -> sum(case when score.score > 60 then 1 else 0 end) / count(1) * 100 as percent
    -> from score group by course_id
    -> order by avg(score) asc, percent desc;
+-----------+-----------+----------+
| course_id | avg_score | percent  |
+-----------+-----------+----------+
|         2 |   27.0000 |   0.0000 |
|         5 |   43.0000 |   0.0000 |
|         7 |   77.0000 | 100.0000 |
|         6 |   82.3333 | 100.0000 |
|         3 |   84.6667 | 100.0000 |
|         4 |  100.0000 | 100.0000 |
+-----------+-----------+----------+
6 rows in set (0.00 sec)

30、课程平均分从高到低显示（现实任课老师）；

mysql> select course_id, avg(score) as avg_score from score
    -> group by course_id
    -> order by avg_score desc ;
+-----------+-----------+
| course_id | avg_score |
+-----------+-----------+
|         4 |  100.0000 |
|         3 |   84.6667 |
|         6 |   82.3333 |
|         7 |   77.0000 |
|         5 |   43.0000 |
|         2 |   27.0000 |
+-----------+-----------+
6 rows in set (0.00 sec)

mysql> select t1.course_id,t1.avg_score,teacher.tname from course,teacher,(
    -> select course_id, avg(score) as avg_score from score
    -> group by course_id
    -> order by avg_score desc)
    -> as t1
    -> where course.cid = t1.course_id and course.teacher_id = teacher.tid
    -> order by t1.avg_score desc;
+-----------+-----------+-----------+
| course_id | avg_score | tname     |
+-----------+-----------+-----------+
|         4 |  100.0000 | 王五      |
|         3 |   84.6667 | 李四      |
|         6 |   82.3333 | 老男孩    |
|         7 |   77.0000 | 小女孩    |
|         5 |   43.0000 | 王五      |
|         2 |   27.0000 | 张三      |
+-----------+-----------+-----------+
6 rows in set (0.00 sec)

31、查询各科成绩前三名的记录(不考虑成绩并列情况)

mysql> select score.sid,score.student_id,score.course_id,score.score,
    -> t1.first_score,t1.second_score,t1.third_score from score
    -> inner join(
    -> select s1.sid,(
    -> select score from score as s2 where s1.course_id = s2.course_id order by score desc limit 0,1)
    -> as first_score,(
    -> select score from score as s3 where s1.course_id = s3.course_id order by score desc limit 1,1)
    -> as second_score,(
    -> select score from score as s4 where s1.course_id = s4.course_id order by score desc limit 2,1)
    -> as third_score from score as s1)
    -> as t1 on score.sid = t1.sid
    -> where score.score in (t1.first_score,t1.second_score,t1.third_score
    -> );
+-----+------------+-----------+-------+-------------+--------------+-------------+
| sid | student_id | course_id | score | first_score | second_score | third_score |
+-----+------------+-----------+-------+-------------+--------------+-------------+
|   4 |          3 |         3 |    88 |          90 |           88 |          76 |
|   5 |          1 |         3 |    76 |          90 |           88 |          76 |
|   6 |          4 |         5 |    34 |          52 |           34 |        NULL |
|   7 |          5 |         6 |    68 |          93 |           86 |          68 |
|   8 |          6 |         6 |    93 |          93 |           86 |          68 |
|   9 |          7 |         7 |    77 |          77 |         NULL |        NULL |
|  10 |          8 |         6 |    86 |          93 |           86 |          68 |
|  11 |          9 |         3 |    90 |          90 |           88 |          76 |
|  12 |         10 |         4 |   100 |         100 |         NULL |        NULL |
|  13 |         11 |         5 |    52 |          52 |           34 |        NULL |
|  14 |         12 |         2 |    27 |          27 |           27 |          27 |
|  15 |          1 |         2 |    27 |          27 |           27 |          27 |
|  16 |          2 |         2 |    27 |          27 |           27 |          27 |
|  17 |          3 |         2 |    27 |          27 |           27 |          27 |
|  18 |          4 |         2 |    27 |          27 |           27 |          27 |
|  19 |          5 |         2 |    27 |          27 |           27 |          27 |
|  20 |          6 |         2 |    27 |          27 |           27 |          27 |
|  21 |          7 |         2 |    27 |          27 |           27 |          27 |
|  22 |          8 |         2 |    27 |          27 |           27 |          27 |
|  23 |          9 |         2 |    27 |          27 |           27 |          27 |
|  24 |         10 |         2 |    27 |          27 |           27 |          27 |
|  25 |         11 |         2 |    27 |          27 |           27 |          27 |
+-----+------------+-----------+-------+-------------+--------------+-------------+
22 rows in set (0.01 sec)

32、查询每门课程被选修的学生数；

mysql> select cname "课程",count(student_id) "选修学生总数" from score LEFT JOIN
    -> course on score.course_id = course.cid
    -> GROUP BY course_id;
+--------+--------------------+
| 课程   | 选修学生总数       |
+--------+--------------------+
| 体育   |                 12 |
| 物理   |                  3 |
| 化学   |                  1 |
| 英语   |                  2 |
| python |                  3 |
| linux  |                  1 |
+--------+--------------------+
6 rows in set (0.00 sec)

33、查询选修了2门以上课程的全部学生的学号和姓名；

mysql> select sid, sname from student
    -> where sid in (
    -> select student_id from score
    -> group by student_id
    -> having count(course_id) > 2
    -> );
Empty set (0.00 sec)

34、查询男生、女生的人数，按倒序排列；

mysql> SELECT sex "性别", count(sid) "总人数" FROM student
    -> GROUP BY sex
    -> ORDER BY count(sid) DESC;
+--------+-----------+
| 性别   | 总人数    |
+--------+-----------+
| 女     |         7 |
| 男     |         5 |
+--------+-----------+
2 rows in set (0.00 sec)

35、查询姓“张”的学生名单；

mysql> select student.sid ,student.sname, student.sex, class.caption from student
    -> inner join class on student.class_id = class.cid
    -> where student.sname like ‘张%‘;
Empty set (0.00 sec)

36、查询同名同姓学生名单，并统计同名人数；

mysql> select sname, count(sname) as count_sname from student
    -> group by sname
    -> having count(sname) > 1;
Empty set (0.00 sec)

37、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(score) as avg_score from score
group by course_id
order by avg_score,course_id desc;

38、查询课程名称为“数学”，且分数低于60的学生姓名和分数；

mysql> select score.student_id, score.score from score
    -> inner join course on score.course_id = course.cid
    -> where course.cname = ‘英语‘ and score.score < 60
    -> ;
+------------+-------+
| student_id | score |
+------------+-------+
|          4 |    34 |
|         11 |    52 |
+------------+-------+
2 rows in set (0.00 sec)

mysql> select student.sname, t1.score from student
    -> inner join (
    -> select score.student_id, score.score from score
    -> inner join course on score.course_id = course.cid
    -> where course.cname = ‘英语‘ and score.score < 60)
    -> as t1
    -> on student.sid = t1.student_id;
+--------+-------+
| sname  | score |
+--------+-------+
| alex   |    34 |
| 丹丹   |    52 |
+--------+-------+
2 rows in set (0.00 sec)

39、查询课程编号为“3”且课程成绩在80分以上的学生的学号和姓名；

mysql> select sid, sname from student
    -> where sid in (
    -> select student_id from score where course_id = 3 and score > 80
    -> );
+-----+-----------+
| sid | sname     |
+-----+-----------+
|   3 | 科比      |
|   9 | 杜拉拉    |
+-----+-----------+
2 rows in set (0.00 sec)

40、求选修了课程的学生人数

mysql> SELECT course_id, count(student_id) as count_student from score
    -> group by course_id;
+-----------+---------------+
| course_id | count_student |
+-----------+---------------+
|         2 |            12 |
|         3 |             3 |
|         4 |             1 |
|         5 |             2 |
|         6 |             3 |
|         7 |             1 |
+-----------+---------------+
6 rows in set (0.00 sec)

41、查询选修“王五”老师所授课程的学生中，成绩最高和最低的学生姓名及其成绩；

mysql> select score.student_id,score.course_id,score.score,t1.max_score,t1.min_score from score,(
    -> select course_id,max(score) as max_score ,min(score) as min_score from score
    -> where course_id in (
    -> select cid from course
    -> inner join teacher on course.teacher_id = teacher.tid
    -> where teacher.tname = ‘王五‘)
    -> group by course_id) as t1
    -> where score.course_id = t1.course_id and score.score in (max_score,min_score)
    -> ;
+------------+-----------+-------+-----------+-----------+
| student_id | course_id | score | max_score | min_score |
+------------+-----------+-------+-----------+-----------+
|         10 |         4 |   100 |       100 |       100 |
|          4 |         5 |    34 |        52 |        34 |
|         11 |         5 |    52 |        52 |        34 |
+------------+-----------+-------+-----------+-----------+
3 rows in set (0.00 sec)

mysql> select student.sname,t2.course_id,t2.score,t2.max_score,t2.min_score from student
    -> inner join (
    -> select score.student_id,score.course_id,score.score,t1.max_score,t1.min_score from score,(
    -> select course_id,max(score) as max_score ,min(score) as min_score from score
    -> where course_id in (
    -> select cid from course
    -> inner join teacher on course.teacher_id = teacher.tid
    -> where teacher.tname = ‘王五‘)
    -> group by course_id) as t1
    -> where score.course_id = t1.course_id and score.score in (max_score,min_score)
    -> )as t2
    -> on student.sid = t2.student_id;
+--------+-----------+-------+-----------+-----------+
| sname  | course_id | score | max_score | min_score |
+--------+-----------+-------+-----------+-----------+
| 姗姗   |         4 |   100 |       100 |       100 |
| alex   |         5 |    34 |        52 |        34 |
| 丹丹   |         5 |    52 |        52 |        34 |
+--------+-----------+-------+-----------+-----------+
3 rows in set (0.00 sec)

42、查询各个课程及相应的选修人数；

mysql> select course.cname,ifnull(t1.count_student,0) as count_student from course
    -> left join (
    -> select course_id, count(student_id) as count_student from score
    -> GROUP BY course_id)
    -> as t1
    -> on course.cid = t1.course_id;
+--------+---------------+
| cname  | count_student |
+--------+---------------+
| 生物   |             0 |
| 体育   |            12 |
| 物理   |             3 |
| 化学   |             1 |
| 英语   |             2 |
| python |             3 |
| linux  |             1 |
+--------+---------------+
7 rows in set (0.00 sec)

43、查询不同课程但成绩相同的学生的学号、课程号、学生成绩；

mysql> select distinct s1.student_id,s2.student_id,s1.course_id as s1_course_id,s2.course_id
    -> as s2_course_id,s1.score,s2.score from score
    -> as s1, score as s2
    -> where s1.course_id != s2.course_id and s1.score = s2.score;
Empty set (0.00 sec)

44、查询每门课程成绩最好的前两名学生id和姓名；

mysql> select student.sid,student.sname,t2.course_id,t2.score,t2.first_score,t2.second_score from student
    -> inner join (
    -> select score.student_id,score.course_id,score.score,t1.first_score,t1.second_score from score
    -> inner join (
    -> select s1.sid,(
    -> select s2.score from score as s2 where s1.course_id = s2.course_id order by s2.score desc limit 0,1) as first_score,(
    -> select s3.score from score as s3 where s1.course_id = s3.course_id order by s3.score desc limit 1,1) as second_score
    -> from score as s1)
    -> as t1 on score.sid = t1.sid
    -> where score.score in (t1.first_score,t1.second_score)
    -> ) as t2
    -> on student.sid = t2.student_id;
+-----+-----------+-----------+-------+-------------+--------------+
| sid | sname     | course_id | score | first_score | second_score |
+-----+-----------+-----------+-------+-------------+--------------+
|   1 | 乔丹      |         2 |    27 |          27 |           27 |
|   2 | 艾弗森    |         2 |    27 |          27 |           27 |
|   3 | 科比      |         3 |    88 |          90 |           88 |
|   3 | 科比      |         2 |    27 |          27 |           27 |
|   4 | alex      |         5 |    34 |          52 |           34 |
|   4 | alex      |         2 |    27 |          27 |           27 |
|   5 | egon      |         2 |    27 |          27 |           27 |
|   6 | egon2     |         6 |    93 |          93 |           86 |
|   6 | egon2     |         2 |    27 |          27 |           27 |
|   7 | kris      |         7 |    77 |          77 |         NULL |
|   7 | kris      |         2 |    27 |          27 |           27 |
|   8 | wxx       |         2 |    27 |          27 |           27 |
|   8 | wxx       |         6 |    86 |          93 |           86 |
|   9 | 杜拉拉    |         2 |    27 |          27 |           27 |
|   9 | 杜拉拉    |         3 |    90 |          90 |           88 |
|  10 | 姗姗      |         2 |    27 |          27 |           27 |
|  10 | 姗姗      |         4 |   100 |         100 |         NULL |
|  11 | 丹丹      |         2 |    27 |          27 |           27 |
|  11 | 丹丹      |         5 |    52 |          52 |           34 |
|  12 | simith    |         2 |    27 |          27 |           27 |
+-----+-----------+-----------+-------+-------------+--------------+
20 rows in set (0.00 sec)

45、检索至少选修两门课程的学生学号；

mysql> select student_id from score
    -> GROUP BY student_id
    -> having count(course_id) >= 2;
+------------+
| student_id |
+------------+
|          1 |
|          3 |
|          4 |
|          5 |
|          6 |
|          7 |
|          8 |
|          9 |
|         10 |
|         11 |
+------------+
10 rows in set (0.00 sec)

46、查询没有学生选修的课程的课程号和课程名；

mysql> SELECT cid, cname from course
    -> where cid not in (
    -> SELECT course_id from score
    -> GROUP BY course_id);
+-----+--------+
| cid | cname  |
+-----+--------+
|   1 | 生物   |
+-----+--------+
1 row in set (0.00 sec)

47、查询没带过任何班级的老师id和姓名；

mysql> SELECT tid, tname from teacher
    -> where tid not in(
    -> select tid from teach2cls
    -> GROUP BY tid);
Empty set (0.00 sec)

48、查询有两门以上课程超过80分的学生id及其平均成绩；

mysql> select student_id, avg(score) as avg_score from score
    -> where student_id in (
    -> select student_id from score
    -> where score > 80
    -> group by student_id
    -> having count(course_id) > 2)
    -> group by student_id;
Empty set (0.00 sec)

49、检索“3”课程分数小于60，按分数降序排列的同学学号；

mysql> select student_id, score from score
    -> where course_id = 3 and score < 60
    -> ORDER BY score DESC;
Empty set (0.00 sec)

50、删除编号为“2”的同学的“1”课程的成绩；

mysql> delete from score where sid = (
    -> select t1.sid from(
    -> select sid from score
    -> where student_id = 2 and course_id = 1) as t1
    -> );
Query OK, 0 rows affected (0.00 sec)

51、查询同时选修了物理课和生物课的学生id和姓名；

mysql> select sid,sname from student
    -> where sid in (
    -> select student_id from score
    -> where course_id in (
    -> select cid from course where course.cname in (‘物理‘,‘生物‘))
    -> GROUP BY student_id
    -> having count(course_id) = 2);
Empty set (0.00 sec)

原文地址：https://www.cnblogs.com/shengyang17/p/8973207.html