mysql數據庫查詢練習45題

時間 2020-06-17

標籤 mysql 數據庫查詢練習欄目 MySQL 简体版

原文原文鏈接

#建學生信息表studentcreate table studenthtml

(spa

sno varchar(20) not null primary key,操作系統

sname varchar(20) not null,3d

ssex varchar(20) not null,htm

sbirthday datetime,blog

class varchar(20)排序

);ci

#創建教師表create table teacherget

(數學

tno varchar(20) not null primary key,

tname varchar(20) not null,

tsex varchar(20) not null,

tbirthday datetime,

prof varchar(20),

depart varchar(20) not null

);

#創建課程表coursecreate table course

(

cno varchar(20) not null primary key,

cname varchar(20) not null,

tno varchar(20) not null,foreign key(tno) references teacher(tno)

);

#創建成績表create table score

(

sno varchar(20) not null primary key,foreign key(sno) references student(sno),

cno varchar(20) not null,foreign key(cno) references course(cno),

degree decimal

);

#添加學生信息insert into student values('108','曾華','男','1977-09-01','95033');insert into student values('105','匡明','男','1975-10-02','95031');insert into student values('107','王麗','女','1976-01-23','95033');insert into student values('101','李軍','男','1976-02-20','95033');insert into student values('109','王芳','女','1975-02-10','95031');insert into student values('103','陸君','男','1974-06-03','95031');

#添加教師表insert into teacher values('804','李誠','男','1958-12-02','副教授','計算機系');insert into teacher values('856','張旭','男','1969-03-12','講師','電子工程系');insert into teacher values('825','王萍','女','1972-05-05','助教','計算機系');insert into teacher values('831','劉冰','女','1977-08-14','助教','電子工程系');

#添加課程表insert into course values('3-105','計算機導論','825');insert into course values('3-245','操做系統','804');insert into course values('6-166','數字電路','856');insert into course values('9-888','高等數學','831');

#添加成績表

insert into score values('103','3-245','86');insert into score values('105','3-245','75');insert into score values('109','3-245','68');insert into score values('103','3-105','92');insert into score values('105','3-105','88');insert into score values('109','3-105','76');insert into score values('103','3-105','64');insert into score values('105','3-105','91');insert into score values('109','3-105','78');insert into score values('103','6-166','85');insert into score values('105','6-166','79');insert into score values('109','6-166','81');

題目：

1、查詢Student表中的全部記錄的Sname、Ssex和Class列。

select sname,ssex,class from student;

2、查詢教師全部的單位即不重複的Depart列。

select distinct depart from teacher;

3、查詢Student表的全部記錄。

select * from student;

4、查詢Score表中成績在60到80之間的全部記錄。

select * from score where degree between 60 and 80;

5、查詢Score表中成績爲85，86或88的記錄

select * from score where degree=85 or degree=86 or degree=88;

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

6、查詢Student表中「95031」班或性別爲「女」的同窗記錄。

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

7、以Class降序查詢Student表的全部記錄。

select * from student order by class desc;

8、以Cno升序、Degree降序查詢Score表的全部記錄。

select * from score order by cno asc,degree desc;

9、查詢「95031」班的學生人數。

select count(*) from student where class='95031';

10、查詢Score表中的最高分的學生學號和課程號。（子查詢或者排序）

select sno,cno from score where degree=(select max(degree) from score);

11、查詢每門課的平均成績。

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

詳解--查詢每門課的平均成績--分組和聚合結合的時候，先分組，而後對每一組分別進行聚合Select AVG(Degree) from Score group by Cno;--先按Cno分組，在對Cno聚合

12、查詢Score表中至少有5名學生選修的並以3開頭的課程的平均分數。

解法1：select * from score where cno in(select cno from score group by cno having count(*)>=5) and cno like '3%';

解法2：select cno,avg(degree) from score where cno like'3%'group by cno having count(*) >=5;

詳解--select Cno,AVG(Degree) from Score where Cno like '3%' group by Cno having COUNT(*)>=5--篩選分組完了再對每一組進行AVG聚合，分完組以後至關於只剩下分完組的列

13、查詢分數大於70，小於90的Sno列。

select sno from score group by sno having min(degree)>70 and max(degree)<90

14、查詢全部學生的Sname、Cno和Degree列。

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

詳解--錶鏈接，必定有主外鍵關係：都好隔開兩個表造成笛卡爾積，再進行where篩選，經過表主外鍵關係篩選，where只是個篩選條件

15、查詢全部學生的Sno、Cname和Degree列。

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

16、查詢全部學生的Sname、Cname和Degree列。

解法1：select student.sname,score.degree,course.cname from student,score,course where score.cno=course.cno and score.sno=student.sno;

解法2：select Sname,Cname,Degree from student join Score on Student.Sno=Score.Sno join Course on Score.Cno=Course.Cno

17、查詢「95033」班學生的平均分。

解法1：select avg(degree) from student,score where student.sno=score.sno and class='95033';

解法2：select avg(degree) from score where sno in(select sno from student where class='95033');

18、假設使用以下命令創建了一個grade表：

create table grade(low int(3),upp int(3),rank char(1))

insert into grade values(90,100,’A’)

insert into grade values(80,89,’B’)

insert into grade values(70,79,’C’)

insert into grade values(60,69,’D’)

insert into grade values(0,59,’E’)

現查詢全部同窗的Sno、Cno和rank列。

解法1：select sno,cno,rank from score,grade where degree between low and upp order by rank;

解法2：select sno,cno,degree,[rank] from Score join grade on degree between low and upp order by [rank]--on後面加篩選條件解法3：select Sno,Cno,(select [rank] from grade where Score.Degree between low and upp) as LV from Score order by Degree desc--子查詢獲得的結果必須惟一

19查詢選修「3-105」課程的成績高於「109」號同窗成績的全部同窗的記錄。

select * from score where cno='3-105' and degree>(select degree from score where sno=109 and cno='3-105');

20、查詢score中選學多門課程的同窗中分數爲非最高分紅績的記錄。

理解1：選學多門課程的同窗中，分數小於全部學生中最高分：
1.select * from score where sno in（2）and degree<（3）

2.select sno from score group by sno having count(*)>1

3.select max(degree) from score where sno in（4）

4.select sno from score group by sno having count(*)>1

結合起來：select * from score where sno in(select sno from score group by sno having count(*)>1) and degree<(select max(degree) from score where sno in(select sno from score group by sno having count(*)>1));

理解2：選多門課程中，分數小於每門課程最高分的學生信息
select * from score a where sno in(select sno from score group by sno having count(*)>1) and degree<(select max(degree) from score b where b.cno = a.cno )

21、查詢成績高於學號爲「109」、課程號爲「3-105」的成績的全部記錄。

select *from score where degree>(select degree from score where sno='109'and Cno='3-105')

22、查詢和學號爲108的同窗同年出生的全部學生的Sno、Sname和Sbirthday列

select sno,sname,sbirthday from student where year(sbirthday)=(select year(sbirthday) from student where sno='108');

23、查詢「張旭「教師任課的學生成績。

1.select * from score where cno in ()2.select cno from course where tno=()3.select tno from teacher where tname='張旭'
結合起來：

select * from score where cno in (select cno from course where tno=(select tno from teacher where tname='張旭'))

解法1：select teacher.tname,course.cno,score.degree from teacher,course,score where teacher.tno=course.tno and course.cno=score.cno and tname='張旭';

解法2：select degree from Score join Course on Score.Cno=Course.Cno join Teacher on Course.Tno=Teacher.Tno where Tname = '張旭'

24、查詢選修某課程的同窗人數多於3人的教師姓名。

1.select tname from teacher where tno=()2.select tno from course where cno=()3.select cno from score group by cno having count(*)>3
聯合起來：

select tname from teacher where tno=(select tno from course where cno=(select cno from score group by cno having count(*)>3))

解法1;select teacher.tname from teacher,score,course where teacher.tno=course.tno and course.cno=score.cno group by tname having count(*)>3 ;

解法2：select Tname from Teacher where Tno=(select Tno from Course where Cno=(select Cno from Score group by Cno having COUNT(Cno)>=3))

2五、查詢95033班和95031班全體學生的記錄。

解法1：select * from student where class='95033' or class='95031';

解法2：select*from student inner join Score on Student.Sno=Score.Sno where Class in(‘95033’,‘95031’)

解法3：select *from Student,Score where Class in(95033,95031) and Student.Sno=Score.Sno

select * from(score left join course on score.cno=course.cno)left join student on score.sno=student.sno where class="95033" or class="95031";

26、查詢存在有85分以上成績的課程Cno.

select score.cno from score,course where score.cno=course.cno and degree>85;

select cno from score group by cno having max(degree)>85;

27、查詢出「計算機系「教師所教課程的成績表

解法1：select degree from teacher,score,course where teacher.tno=course.tno and course.cno=score.cno and teacher.depart='計算機系';

解法2：select *from Score where Cno in( select Cno from Course where Tno in (select Tno from Teacher where Depart='計算機系'))解法3：select Sno,Score.Cno,Degree from Score join Course on Score.Cno=Course.Cno join Teacher on Course.Tno=Teacher.Tno where Depart='計算機系'

2八、查詢「計算機系」與「電子工程系「不一樣職稱的教師的Tname和Prof。

解法1：select tname,prof from teacher where depart='計算機系' and prof not in (select prof from teacher where depart='電子工程系');

解法2：select tname,prof from teacher where prof not in

(select prof from teacher where depart='電子工程系' and prof in (select prof from teacher where depart='計算機系'))and depart in ('計算機系','電子工程系')--查詢兩個系中教師相同職稱名稱，不在這裏面的就是除去兩個系都有的剩下的，見上面select prof from teacher where depart='電子工程系' and prof in (select prof from teacher where depart='計算機系')

29、查詢選修編號爲「3-105「課程且成績至少高於選修編號爲「3-245」的同窗的Cno、Sno和Degree,並按Degree從高到低次序排序。（any的用法）

解法1；select * from score where cno='3-105' and degree > (select min(degree) from score where cno='3-245')order by degree desc;

解法2：select * from score where cno='3-105' and degree > any(select degree from score where cno='3-245')order by degree desc;

30、查詢選修編號爲「3-105」且成績高於選修編號爲「3-245」課程的同窗的Cno、Sno和Degree.（all的用法）

select * from score where cno='3-105' and degree > (select max(degree) from score where cno='3-245');

select * from score where cno='3-105' and degree > all(select degree from score where cno='3-245');

31、查詢全部教師和同窗的name、sex和birthday.

select tname,tsex,tbirthday from teacherunionselect sname,ssex,sbirthday from student

32、查詢全部「女」教師和「女」同窗的name、sex和birthday.

select tname,tsex,tbirthday from teacher where tsex='女'union select sname,ssex,sbirthday from student where ssex='女'

33、查詢成績比該課程平均成績低的同窗的成績表。

select * from score as aa where degree<(select avg(degree) from score as bb where aa.cno=bb.cno);

解法2：詳解--相關子查詢--同一門學科的平均分,，每門學科低於自身平均分的select * from score as a where a.degree<

(select AVG(degree) from score as b where a.cno = b.cno group by cno)--至關於foreach列出每一門課的平均分select * from score as a where a.degree<

(select AVG(degree) from score as b group by cno having a.cno = b.cno)

34、查詢全部任課教師的Tname和Depart

解法1：select tname,depart from teacher where exists (select * from course where teacher.tno=course.tno);

解法2：select Tname,Depart from Teacher where Tno in(select distinct Tno from Course)

35 、查詢全部未講課的教師的Tname和Depart.

解法1：select tname,depart from teacher where not exists (select * from course where teacher.tno=course.tno);

36、查詢至少有2名男生的班號。

select class from student where ssex='男'group by class having count(*)>=2;

37、查詢Student表中不姓「王」的同窗記錄。

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

38、查詢Student表中每一個學生的姓名和年齡。

select sname,year(now())-year(sbirthday) from student;

39、查詢Student表中最大和最小的Sbirthday日期值。

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

40、以班號和年齡從大到小的順序查詢Student表中的所有記錄。

select * from student order by class desc,date(sbirthday) asc;

41、查詢「男」教師及其所上的課程。

解法1：select teacher.tname,teacher.tsex,course.cname from teacher,course where teacher.tno=course.tno and tsex='男';

解法2：select teacher.tno,tname,tsex,cname,cno from teacher join course on teacher.tno=course.tno where tsex='男'

42、查詢最高分同窗的Sno、Cno和Degree列。

select sno,cno,degree from score where degree=(select max(degree) from score);

43、查詢和「李軍」同性別的全部同窗的Sname.

select sname from student where ssex=(select ssex from student where sname='李軍');

44、查詢和「李軍」同性別並同班的同窗Sname.

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

45、查詢全部選修「計算機導論」課程的「男」同窗的成績表。

select student.sname,score.degree from student,score,course where student.sno=score.sno and course.cno=score.cno and course.cname='計算機導論' and student.ssex='男';

select * from score where sno in(select sno from student where ssex='男') and cno=(select cno from course where cname='計算機導論')