6、MySQL测试题

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6、MySQL测试题

曲~线 2018-09-16 21:40:00 浏览1273
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MySQL测试题

一、表关系

img_a8ceb305627360e9058a94310b88b2ba.png
表关系

请创建如下表,并创建相关约束

二、操作表

1、自行创建测试数据

2、查询“生物”课程比“物理”课程成绩高的所有学生的学号;

3、查询平均成绩大于60分的同学的学号和平均成绩;

4、查询所有同学的学号、姓名、选课数、总成绩;

5、查询姓“李”的老师的个数;

6、查询没学过“叶平”老师课的同学的学号、姓名;

7、查询学过“001”并且也学过编号“002”课程的同学的学号、姓名;

8、查询学过“叶平”老师所教的所有课的同学的学号、姓名;

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;

10、查询有课程成绩小于60分的同学的学号、姓名;

11、查询没有学全所有课的同学的学号、姓名;

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;

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;

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;

15、删除学习“叶平”老师课的SC表记录;

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;

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;

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;

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;

20、课程平均分从高到低显示(现实任课老师);

21、查询各科成绩前三名的记录:(不考虑成绩并列情况)

22、查询每门课程被选修的学生数;

23、查询出只选修了一门课程的全部学生的学号和姓名;

24、查询男生、女生的人数;

25、查询姓“张”的学生名单;

26、查询同名同姓学生名单,并统计同名人数;

27、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;

28、查询平均成绩大于85的所有学生的学号、姓名和平均成绩;

29、查询课程名称为“数学”,且分数低于60的学生姓名和分数;

30、查询课程编号为003且课程成绩在80分以上的学生的学号和姓名;

31、求选了课程的学生人数

32、查询选修“杨艳”老师所授课程的学生中,成绩最高的学生姓名及其成绩;

33、查询各个课程及相应的选修人数;

34、查询不同课程但成绩相同的学生的学号、课程号、学生成绩;

35、查询每门课程成绩最好的前两名;

36、检索至少选修两门课程的学生学号;

37、查询全部学生都选修的课程的课程号和课程名;

38、查询没学过“叶平”老师讲授的任一门课程的学生姓名;

39、查询两门以上不及格课程的同学的学号及其平均成绩;

40、检索“004”课程分数小于60,按分数降序排列的同学学号;

41、删除“002”同学的“001”课程的成绩;

1、自行创建测试数据
2、查询“生物”课程比“物理”课程成绩高的所有学生的学号;
思路:
获取所有有生物课程的人(学号,成绩) - 临时表
获取所有有物理课程的人(学号,成绩) - 临时表
根据【学号】连接两个临时表:
学号 物理成绩 生物成绩

然后再进行筛选

select A.student_id,sw,ty from

(select student_id,num as sw from score left join course on score.course_id = course.cid where course.cname = '生物') as A

left join

(select student_id,num  as ty from score left join course on score.course_id = course.cid where course.cname = '体育') as B

on A.student_id = B.student_id where sw > if(isnull(ty),0,ty);

3、查询平均成绩大于60分的同学的学号和平均成绩;
思路:
根据学生分组,使用avg获取平均值,通过having对avg进行筛选

select student_id,avg(num) from score group by student_id having avg(num) > 60

4、查询所有同学的学号、姓名、选课数、总成绩;

select score.student_id,sum(score.num),count(score.student_id),student.sname
from
score left join student on score.student_id = student.sid  
group by score.student_id

5、查询姓“李”的老师的个数;

select count(tid) from teacher where tname like '李%'

select count(1) from (select tid from teacher where tname like '李%') as B

6、查询没学过“叶平”老师课的同学的学号、姓名;
思路:
先查到“李平老师”老师教的所有课ID
获取选过课的所有学生ID
学生表中筛选

select * from student where sid not in (
select DISTINCT student_id from score where score.course_id in (
select cid from course left join teacher on course.teacher_id = teacher.tid where tname = '李平老师'
)
)

7、查询学过“001”并且也学过编号“002”课程的同学的学号、姓名;
思路:
先查到既选择001又选择002课程的所有同学
根据学生进行分组,如果学生数量等于2表示,两门均已选择

select student_id,sname from

(select student_id,course_id from score where course_id = 1 or course_id = 2) as B

left join student on B.student_id = student.sid group by student_id HAVING count(student_id) > 1

8、查询学过“叶平”老师所教的所有课的同学的学号、姓名;

同上,只不过将001和002变成 in (叶平老师的所有课)

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;
同第1题

10、查询有课程成绩小于60分的同学的学号、姓名;

select sid,sname from student where sid in (
select distinct student_id from score where num < 60
)

11、查询没有学全所有课的同学的学号、姓名;
思路:
在分数表中根据学生进行分组,获取每一个学生选课数量
如果数量 == 总课程数量,表示已经选择了所有课程

select student_id,sname
from score left join student on score.student_id = student.sid
group by student_id HAVING count(course_id) = (select count(1) from course)

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;
思路:
获取 001 同学选择的所有课程
获取课程在其中的所有人以及所有课程
根据学生筛选,获取所有学生信息
再与学生表连接,获取姓名

select student_id,sname, count(course_id)
from score left join student on score.student_id = student.sid
where student_id != 1 and course_id in (select course_id from score where student_id = 1) group by student_id

13、查询至少学过学号为“001”同学所有课的其他同学学号和姓名;
先找到和001的学过的所有人
然后个数 = 001所有学科 ==》 其他人可能选择的更多

select student_id,sname, count(course_id)
from score left join student on score.student_id = student.sid
where student_id != 1 and course_id in (select course_id from score where student_id = 1) group by student_id having count(course_id) = (select count(course_id) from score where student_id = 1)

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;

个数相同
002学过的也学过

select student_id,sname from score left join student on score.student_id = student.sid where student_id in (
select student_id from score  where student_id != 1 group by student_id HAVING count(course_id) = (select count(1) from score where student_id = 1)
) and course_id in (select course_id from score where student_id = 1) group by student_id HAVING count(course_id) = (select count(1) from score where student_id = 1)

15、删除学习“叶平”老师课的score表记录;

delete from score where course_id in (
select cid from course left join teacher on course.teacher_id = teacher.tid where teacher.name = '叶平'
)

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;
思路:
由于insert 支持
inset into tb1(xx,xx) select x1,x2 from tb2;
所有,获取所有没上过002课的所有人,获取002的平均成绩

insert into score(student_id, course_id, num) select sid,2,(select avg(num) from score where course_id = 2)
from student where sid not in (
select student_id 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;

select sc.student_id,
(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,
(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,
(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,
count(sc.course_id),
avg(sc.num)
from score as sc
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;

select course_id, max(num) as max_num, min(num) as 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;
思路:case when .. then

select course_id, avg(num) as avgnum,sum(case when score.num > 60 then 1 else 0 END)/count(1)*100 as percent from score group by course_id order by avgnum asc,percent desc;

20、课程平均分从高到低显示(现实任课老师);

select avg(if(isnull(score.num),0,score.num)),teacher.tname from course
left join score on course.cid = score.course_id
left join teacher on course.teacher_id = teacher.tid

group by score.course_id

21、查询各科成绩前三名的记录:(不考虑成绩并列情况)

select score.sid,score.course_id,score.num,T.first_num,T.second_num from score left join
(
select
sid,
(select num from score as s2 where s2.course_id = s1.course_id order by num desc limit 0,1) as first_num,
(select num from score as s2 where s2.course_id = s1.course_id order by num desc limit 3,1) as second_num
from
score as s1
) as T
on score.sid =T.sid
where score.num <= T.first_num and score.num >= T.second_num

22、查询每门课程被选修的学生数;

select course_id, count(1) from score group by course_id;

23、查询出只选修了一门课程的全部学生的学号和姓名;

select student.sid, student.sname, count(1) from score

left join student on score.student_id  = student.sid

group by course_id having count(1) = 1

24、查询男生、女生的人数;

select * from
(select count(1) as man from student where gender='男') as A ,
(select count(1) as feman from student where gender='女') as B

25、查询姓“张”的学生名单;

select sname from student where sname like '张%';

26、查询同名同姓学生名单,并统计同名人数;

select sname,count(1) as count from student group by sname;

27、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(if(isnull(num), 0 ,num)) as avg from score group by course_id order by avg     asc,course_id desc;

28、查询平均成绩大于85的所有学生的学号、姓名和平均成绩;

select student_id,sname, avg(if(isnull(num), 0 ,num)) from score left join student on score.student_id = student.sid group by student_id;

29、查询课程名称为“数学”,且分数低于60的学生姓名和分数;

select student.sname,score.num from score
left join course on score.course_id = course.cid
left join student on score.student_id = student.sid
where score.num < 60 and course.cname = '生物'

30、查询课程编号为003且课程成绩在80分以上的学生的学号和姓名;

select * from score where score.student_id = 3 and score.num > 80

31、求选了课程的学生人数

select count(distinct student_id) from score

select count(c) from (
select count(student_id) as c from score group by student_id) as A

32、查询选修“杨艳”老师所授课程的学生中,成绩最高的学生姓名及其成绩;

select sname,num from score
left join student on score.student_id = student.sid
where score.course_id in (select course.cid from course left join teacher on course.teacher_id = teacher.tid where tname='张磊老师') order by num desc limit 1;

33、查询各个课程及相应的选修人数;

select course.cname,count(1) from score
left join course on score.course_id = course.cid
group by course_id;

34、查询不同课程但成绩相同的学生的学号、课程号、学生成绩;

select DISTINCT s1.course_id,s2.course_id,s1.num,s2.num from score as s1, score as s2 where s1.num = s2.num and s1.course_id != s2.course_id;

35、查询每门课程成绩最好的前两名;

select score.sid,score.course_id,score.num,T.first_num,T.second_num from score left join
(
select
sid,
(select num from score as s2 where s2.course_id = s1.course_id order by num desc limit 0,1) as first_num,
(select num from score as s2 where s2.course_id = s1.course_id order by num desc limit 1,1) as second_num
from
score as s1
) as T
on score.sid =T.sid
where score.num <= T.first_num and score.num >= T.second_num

36、检索至少选修两门课程的学生学号;

select student_id from score group by student_id having count(student_id) > 1

37、查询全部学生都选修的课程的课程号和课程名;

select course_id,count(1) from score group by course_id having count(1) = (select count(1) from student);

38、查询没学过“叶平”老师讲授的任一门课程的学生姓名;

select student_id,student.sname from score
left join student on score.student_id = student.sid
where score.course_id not in (
select cid from course left join teacher on course.teacher_id = teacher.tid where tname = '张磊老师'
)
group by student_id

39、查询两门以上不及格课程的同学的学号及其平均成绩;

select student_id,count(1) from score where num < 60 group by student_id having count(1) > 2

40、检索“004”课程分数小于60,按分数降序排列的同学学号;

select student_id from score where num< 60 and course_id = 4 order by num desc;

41、删除“002”同学的“001”课程的成绩;

delete from score where course_id = 1 and student_id = 2

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