MySql——查询题目练习

本次查询我们基于这几张表查询

***********查询练习**********

1、 查询Student表中的所有记录的Sname、Ssex和Class列。

select sname,ssex,class from student;

2、 查询教师所有的单位即不重复的Depart列。

select distinct depart from teacher;

3、 查询Student表的所有记录。

select * from student;

4、 查询Score表中成绩在60到80之间的所有记录。

Select * from score where degree between 60 and 80;

5、 查询Score表中成绩为85，86或88的记录。

Select * from score where degree in(85,86,88);

6、 查询Student表中“95031”班或性别为“女”的同学记录。

select * from student where class=”95031” or ssex=”女” ;

7、 以Class降序查询Student表的所有记录。

Select * from student order by class desc;

8、 以Cno升序、Degree降序查询Score表的所有记录。

Select * from score order by cno, degree desc;

9、 查询“95031”班的学生人数。

select count(*) from student where class = '';

10、 查询Score表中的最高分的学生学号和课程号。（子查询或者排序）

Select sno,cno,max(degree) from score group by cno;

11、 查询每门课的平均成绩。

Select cno,avg(degree) from score group by cno;

12、查询Score表中至少有5名学生选修的并以3开头的课程的平均分数。

Select cno,avg(degree) from score where (select count(sno) from score )

至少有五名同学选修的课程：

Select cno, count(sno)>=5,avg(degree) from score where cno like’ 3%’ ;

13、查询分数大于70，小于90的Sno列。

Select sno from score where degree >70 and degree<90;

14、查询所有学生的Sname、Cno和Degree列。

Select sname,cno,degree from student,score where student.sno=score.sno;

15、查询所有学生的Sno、Cname和Degree列。

Select sno,cname,degree from score,course  where course.cno=score.cno;

16、查询所有学生的Sname、Cname和Degree列。

Select sname,cname,degree from student,course,score where student.sno=score.sno and course.cno=score.cno;

17、查询“95033”班学生的平均分。

Select class,avg(degree)  from student,score where student.sno=score.sno class=’95033’;

18、查询选修“3-105”课程的成绩高于“109”号同学成绩的所有同学的记录。

Select * from student,score where student.sno=score.sno and cno=’3-105’ and degree>(select degree from score where sno=’109’ and cno=’3-105’);

19、查询score中选学多门课程的同学中分数为非最高分成绩的记录。

先取出每科成绩的最高成绩

Select cno,max(degree) from score group by cno having count(*)>1;

select score.sno,score.cno,score.degree from score

join

(Select cno,max(degree) as big from score group by cno having count(*)>1)as a

on

score.cno = a.cno and score.degree <> a.big;

20、查询成绩高于学号为“109”、课程号为“3-105”的成绩的所有记录

Select * from score where cno='3-105' and degree>(select degree from score where sno='' and cno='3-105');

21、查询和学号为108的同学同年出生的所有学生的Sno、Sname和Sbirthday列。

Select * from student where sbirthday=(select sbiryhday from student where sno=’108’);

22、查询“张旭“教师任课的学生成绩（姓名）。

先找出该老师的课程编号；

Select cno from course where tno=(select tno from teacher where tname=’张旭’);

汇总：

Select sname,degree from student,score

where student.sno=score.sno

and cno=(Select cno from course where tno=(select tno from teacher where tname='张旭'));

23、查询考计算机导论的学生成绩

先找到计算机导论的课程编号

select cno from course where cname=('计算机导论');

Select sno,degree from score where cno= (select cno from course where cname=('计算机导论'));

24、课程名(cname)称为计算机导论 的课程编号

Select cno from course where cname=(‘计算机导论’);

25、查询李诚老师教的课程名称

select tno from teacher where tname=(‘李诚’);

Select cname from course where tno=(select tno from teacher where tname=(‘李诚’));

26、教高等数学的老师是哪个系的

Select tno from course where cname=(‘高等数学’);

Select depart from teacher where tno=(Select tno from course where cname=(‘高等数学’));

27、查询选修某课程的同学人数多于5人的教师姓名。

select cno from score group by cno having count(sno)>5;

select tname from teacher where tno=(select tno from course where cno=(select cno from score group by cno having count(sno)>5));

28、查询95033班和95031班全体学生的记录。

Select * from student where class in(95033,95031);

29、查询成绩表中存在有85分以上成绩的课程Cno.

Select cno from score where degree>85;

30、查询出“计算机系“教师所教课程的成绩表。

Select * from score where cno in ();

Select cno from course where tno in();

Select tno from teacher where depart=’计算机系’;

Select * from score where cno in (Select cno from course where tno in(Select tno from teacher where depart=’计算机系’));

31、查询选修编号为“3-105”且成绩高于选修编号为“3-245”课程的同学的Cno、Sno和Degree.

根据3-105找信息并且成绩还有要求

Select min(degree) from score where cno='3-245';

Select * from score where cno=’3-105’ and degree>(Select min(degree) from score where cno='3-245');

32、查询所有教师和同学的name、sex和birthday.

select sname,ssex,sbirthday from student

union

select tname,tsex,tbirthday from teacher;

33、查询所有“女”教师和“女”同学的name、sex和birthday.

select sname,ssex,sbirthday from student where ssex='女'

union

select tname,tsex,tbirthday from teacher  where tsex='女';

34、查询所有成绩 比3-105课程平均成绩低的同学的成绩表。

Select * from score where degree <(Select avg(degree) from score where cno='3-105');

35、查询所有任课教师的Tname和Depart.

Select tname,depart from teacher;

36、查询所有未讲课的教师的Tname和Depart.

Select tname,depart from teacher where tno in (select tno from course where cno not in(select cno from score));

37、查询至少有2名男生的班号。(根据性别班级分)

Select class,count(ssex=’男’) >=2 from student;

38、查询Student表中不姓“王”的同学记录。

Select * from student where sname not like '王%';

39、查询Student表中每个学生的姓名和年龄。

Select sname, (year(now())-year(sbirthday)) as old from student;

40、查询Student表中最大和最小的Sbirthday日期值。

select max(sbirthday),min(sbirthday)    from student;

41、以班号和年龄从大到小的顺序查询Student表中的全部记录。

Select * ,(year(now())-year(sbirthday)) as old from student order by  class desc,old desc;

42、查询“男”教师及其所上的课程。

Select tno from teacher where tsex= '男';

Select cno,cname from course where tno in (Select tno from teacher where tsex= '男');

43、查询最高分同学的Sno、Cno和Degree列。

Select * from score where degree=(select max(degree) from score);

44、查询和“李军”同性别的所有同学的Sname.

Select * from student where ssex=(select ssex from student where sname= '李军');

45、查询和“李军”同性别并同班的同学Sname.

Select sname from student where class=(select class from student where sname= '李军') and ssex=(select ssex from student where sname= '李军');

46、查询所有选修“计算机导论”课程的“男”同学的成绩表。

Select cno from course where cname= '计算机导论'

Select sno from student where ssex= '男'

Select * from score where cno in (Select cno from course where cname= '计算机导论')

And sno  in (Select sno from student where ssex= '男');