Python/ MySQL练习题

Posted 2020-09-22

Python/ MySQL练习题（一）

2、查询“生物”课程比“物理”课程成绩高的所有学生的学号

 1 SELECT
 2     *
 3 FROM
 4     (
 5         SELECT
 6             *
 7         FROM
 8             course
 9         LEFT JOIN score ON score.course_id = course.cid
10         WHERE
11             course.cname = ‘生物‘
12     ) AS A
13 INNER JOIN (
14     SELECT
15         *
16     FROM
17         course
18     LEFT JOIN score ON score.course_id = course.cid
19     WHERE
20         course.cname = ‘物理‘
21 ) AS B ON A.student_id = B.student_id
22 WHERE
23     A.num > B.num

 

 3、查询平均成绩大于60分的同学的学号和平均成绩

 1 SELECT
 2     B.student_id,
 3     student.sname,
 4     B.cc
 5 FROM
 6     (
 7         SELECT
 8             student_id,
 9             num,
10             avg(num) AS cc
11         FROM
12             score
13         GROUP BY
14             student_id
15         HAVING
16             avg(num) > 60
17     ) AS B
18 LEFT JOIN student ON B.student_id = student.sid

 4、查询所有同学的学号、姓名、选课数、总成绩

 1 SELECT
 2     student_id,
 3     student.sname,
 4     count(score.course_id)as cc,
 5     sum(num)as cj
 6 FROM
 7     student
 8 LEFT JOIN score ON score.student_id = student.sid
 9 GROUP BY
10     score.student_id

 5、查询姓“李”的老师的个数

1 SELECT * from teacher where tname like ‘李%‘

6、查询没学过“李平”老师课的同学的学号、姓名

 1 SELECT student.sid,student.sname from student where sid not in
 2 (SELECT
 3     student_id
 4 FROM
 5 score
 6 WHERE course_id IN
 7     (
 8         SELECT
 9             course.cid
10         FROM
11             course
12         LEFT JOIN teacher ON teacher.tid = course.teacher_id
13         WHERE
14             tname = ‘李平老师‘
15     ) GROUP BY student_id)

7、查询学过“001”并且也学过编号“002”课程的同学的学号、姓名

1 select A.student_id,B.sname FROM (SELECT score.student_id,student.sname,course_id
2  from score LEFT JOIN student on student.sid=score.student_id where score.course_id=‘1‘)as A
3  LEFT JOIN(SELECT score.student_id,student.sname,course_id
4  from score LEFT JOIN student on student.sid=score.student_id where score.course_id=‘2‘)as B
5  on A.student_id=B.student_id
6 where A.course_id=1 and B.course_id=2;

 8、查询学过“李平”老师所教的所有课的同学的学号、姓名

 1 SELECT
 2     student.sid,
 3     student.sname
 4 FROM
 5     student
 6 WHERE
 7     student.sid NOT IN (
 8         SELECT
 9             student.sname
10         FROM
11             student
12         WHERE
13             student.sid IN (
14                 SELECT
15                     course.cid
16                 FROM
17                     course
18                 LEFT JOIN teacher ON teacher.tid = course.teacher_id
19                 WHERE
20                     teacher.tname = ‘李平老师‘
21             )
22     )

9、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

 1 SELECT
 2     student.sid,
 3     student.sname
 4 FROM
 5     (
 6         SELECT
 7             *
 8         FROM
 9             score
10         WHERE
11             score.course_id = ‘2‘
12     ) AS A
13 LEFT JOIN (
14     SELECT
15         *
16     FROM
17         score
18     WHERE
19         score.course_id = ‘1‘
20 ) AS B ON A.student_id = B.student_id
21 LEFT JOIN student ON student.sid = B.student_id
22 WHERE
23     A.num < B.num

10、查询有课程成绩小于60分的同学的学号、姓名

 1 SELECT
 2     student.sid,
 3     student.sname
 4 FROM
 5     score
 6 LEFT JOIN course ON course.cid = score.course_id
 7 LEFT JOIN student ON student.sid = score.student_id
 8 WHERE
 9     score.num < 60
10 GROUP BY
11     student_id

11、查询没有学全所有课的同学的学号、姓名

 1 SELECT
 2     student.sid,
 3     student.sname
 4 FROM
 5     student
 6 WHERE
 7     student.sid NOT IN (
 8         SELECT
 9             student.sid
10         FROM
11             score
12         LEFT JOIN course ON course.cid = score.course_id
13         LEFT JOIN student ON student.sid = score.student_id
14         GROUP BY
15             score.student_id
16         HAVING
17             count(course_id) = (SELECT COUNT(cid) FROM course)
18     )

12、查询至少有一门课与学号为“001”的同学所学相同的同学的学号和姓名

 1   SELECT
 2 *
 3  FROM
 4     score
 5     LEFT JOIN student on score.student_id = student.sid
 6     LEFT JOIN course ON course.cid = score.course_id
 7  WHERE student_id != 1 AND
 8 score.course_id  in  (
 9         SELECT
10             course_id
11         FROM
12             score
13         WHERE
14             student_id = 1
15 )
16 GROUP BY student_id

 13、查询至少学过学号为“001”同学所选课程中任意一门课的其他同学学号和姓名

1 SELECT student_id from score where student_id!=1 and course_id IN
2 (select course_id from score where student_id =1 GROUP BY course_id)
3 GROUP BY student_id

14、查询和“002”号的同学学习的课程完全相同的其他同学学号和姓名

 1 SELECT
 2     student_id,
 3     sname
 4 FROM
 5     score
 6 LEFT JOIN student ON score.student_id = student.sid
 7 WHERE
 8     student_id IN (
 9         SELECT
10             student_id
11         FROM
12             score
13         WHERE
14             student_id != 1
15         GROUP BY
16             student_id
17         HAVING
18             count(course_id) = (
19                 SELECT
20                     count(1)
21                 FROM
22                     score
23                 WHERE
24                     student_id = 1
25             )
26     )
27 AND course_id IN (
28     SELECT
29         course_id
30     FROM
31         score
32     WHERE
33         student_id = 1
34 )
35 GROUP BY
36     student_id
37 HAVING
38     count(course_id) = (
39         SELECT
40             count(1)
41         FROM
42             score
43         WHERE
44             student_id = 1
45     )

15、删除学习“李平”老师课的SC表记录

1  DELETE FROM score where score.course_id IN
2  (SELECT course_id from course LEFT JOIN teacher  on teacher.tid=course.teacher_id
3  LEFT JOIN score on score.course_id=course.cid
4  LEFT JOIN student  on score.student_id=student.sid
5  WHERE teacher.tname=‘李平老师‘
6 GROUP BY course_id;)

16、向SC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“002”课程的同学学号；②插入“002”号课程的平均成绩

1 insert into score (student_id,course_id,num)SELECT student_id,1,FLOOR(avg(num))
2 (SELECT student_id from score where course_id !=2
3 SELECT FLOOR(avg(num))from score where course_id = 2)

17、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

1     select sc.student_id,
2         (select num from score left join course on score.course_id = course.cid where course.cname = "生物" and score.student_id=sc.student_id) as sy,
3         (select num from score left join course on score.course_id = course.cid where course.cname = "物理" and score.student_id=sc.student_id) as wl,
4         (select num from score left join course on score.course_id = course.cid where course.cname = "体育" and score.student_id=sc.student_id) as ty,
5         count(sc.course_id),
6         avg(sc.num)
7     from score as sc
8     group by student_id desc        

18、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

1 select student_id,MAX(num),MIN(num) from score GROUP BY course_id

19、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

 1 SELECT
 2     course_id,
 3     avg(num) AS nn,
 4     sum(
 5         CASE
 6         WHEN num < 60 THEN
 7             0
 8         ELSE
 9             1
10         END
11     ),
12     SUM(1),
13     sum(
14         CASE
15         WHEN num < 60 THEN
16             0
17         ELSE
18             1
19         END
20     ) / SUM(1) AS pj
21 FROM
22     score
23 GROUP BY
24     course_id
25 ORDER BY
26     avg(num) DESC

20、课程平均分从高到低显示（现实任课老师）

1 SELECT score.course_id,course.cname,avg(num),teacher.tname from score LEFT JOIN course on course.cid=score.course_id
2 LEFT JOIN teacher on teacher.tid=course.teacher_id
3 GROUP BY course_id
4 
5 HAVING avg(num)
6 ORDER BY avg(num) DESC