php 查询45题

Posted 2020-07-14 哔哩哔哩干杯

表格代码

create table student
(
    sno varchar(20) primary key,
    sname varchar(20) not null,
    ssex varchar(20) not null,
    sbirthday datetime,
    class varchar(20)
)
;
create table teacher
(
    tno varchar(20) primary key,
    tname varchar(20) not null,
    tsex varchar(20) not null,
    tbirthday datetime,
    prof varchar(20),
    depart varchar(20) not null
)
;
create table course
(
    cno varchar(20) primary key,
    cname varchar(20) not null,
    tno varchar(20) not null,
    foreign key(tno) references teacher(tno)
    
)
;
create table score
(
    sno varchar(20) not null,
    cno varchar(20) not null,
    degree decimal(4,1),
    foreign key(sno) references student(sno),
    foreign key(cno) references course(cno),
    primary key(sno,cno)
)
;


insert into student values(\'108\',\'曾华\',\'男\',\'1977-09-01\',\'95033\');
insert into student values(\'105\',\'匡明\',\'男\',\'1975-10-02\',\'95031\');
insert into student values(\'107\',\'王丽\',\'女\',\'1976-01-23\',\'95033\');
insert into student values(\'101\',\'李军\',\'男\',\'1976-02-20\',\'95033\');
insert into student values(\'109\',\'王芳\',\'女\',\'1975-02-10\',\'95031\');
insert into student values(\'103\',\'陆君\',\'男\',\'1974-06-03\',\'95031\');

insert into teacher values(\'804\',\'李诚\',\'男\',\'1958-12-02\',\'副教授\',\'计算机系\');
insert into teacher values(\'856\',\'张旭\',\'男\',\'1969-03-12\',\'讲师\',\'电子工程系\');
insert into teacher values(\'825\',\'王萍\',\'女\',\'1972-05-05\',\'助教\',\'计算机系\');
insert into teacher values(\'831\',\'刘冰\',\'女\',\'1977-08-14\',\'助教\',\'电子工程系\');

insert into course values(\'3-105\',\'计算机导论\',\'825\');
insert into course values(\'3-245\',\'操作系统\',\'804\');
insert into course values(\'6-166\',\'数字电路\',\'856\');
insert into course values(\'9-888\',\'高等数学\',\'831\');

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(\'101\',\'3-105\',\'64\');
insert into score values(\'107\',\'3-105\',\'91\');
insert into score values(\'108\',\'3-105\',\'78\');
insert into score values(\'101\',\'6-166\',\'85\');
insert into score values(\'107\',\'6-166\',\'79\');
insert into score values(\'108\',\'6-166\',\'81\');

View Code

题目答案

1.select sname,ssex,class from student
2.select distinct depart from teacher
3.select * from student
4.select * from score where degree>60 and degree<80
5.select * from score where degree in(85,86,88)
6.select * from student where class=\'95031\' or ssex=\'女\'
7.select * from student order by class desc
8.select * from score order by cno asc,degree desc
9.select * from student where class=\'95031\'
10.select * from score order by degree desc
11.我的方法：select avg(degree) from score where cno=\'3-245\'
select avg(degree) from score where cno=\'3-105\'
select avg(degree) from score where cno=\'6-166\'
答案：select Cno,avg(Degree) from Score group by Cno
12.这个题不会
答案：select avg(Degree) from Score where Cno in (select Cno from Score group by Cno having count(*)>5) and Cno like \'3%\' group by Cno
13.select sno from score where degree>70 and degree<90
14.select sname,cno,degree from score join student on student.sno=score.sno
15.select sno,cname,degree from score join course on course.cno=score.cno
16.这个题做错了
我的答案：select sname,cname,degree from score join student,course on(student.sno=score.sno and course.cno=score.cno)
正确答案：select Sname,Cname,Degree from Score join Student on Student.Sno = Score.Sno join Course on Score.Cno = Course.Cno
不能写在一起
17.select avg(degree) from score where sno in(select sno from student where class=\'95033\')
18.这个题写不出
答案：select Sno,Cno,rank from Score join grade on Score.Degree between low and upp
19.select * from score where cno =\'3-105\' and degree>(select degree from score where sno = \'109\' and cno = \'3-105\')
若果没写后面的cno = \'3-105\' 软件就会崩溃 不知道为什么 试了好几次 0v0
20.这题只会写前半部分 OTZ
答案：理解1
select * from Score a where Sno in (select Sno from Score group by Sno having count(*)>1 ) and Degree not in (select max(Degree) from Score b where b.Cno = a.Cno)
理解2
select * from Score a where Sno in (select Sno from Score group by Sno having count(*)>1 ) and Degree not in (select max(Degree) from Score a where Sno in (select Sno from Score group by Sno having count(*)>1 ))
21.弄不懂和19题有啥区别 理解不能
答案：select * from Score where Degree >(select Degree from Score where Sno = \'109\' and Cno = \'3-105\')
22.还是写不出...
答案：select Sno,Sname,Sbirthday from Student where YEAR(Sbirthday) = (select YEAR(Sbirthday) from Student where Sno = \'108\')
23.关联了3个表 想的出来 但写不出来
答案：select * from Score where Cno in(select Cno from Course where Tno =(select Tno from Teacher where Tname=\'张旭\'))
24.select tname from teacher where tno in(select tno from course where cno in(select cno from score group by cno having count(*) > 5))
25.select * from Student where Class in(\'95031\',\'95033\')
突然又变简单了
26.select distinct Cno from Score where Degree > 85
27.select * from Score where Cno in(select Cno from Course where Tno in(select Tno from Teacher where depart = \'计算机系\'))
28.依旧写不出...
答案：select Tname,prof from Teacher where prof not in(select prof from Teacher where depart = \'计算机系\' and prof in(select prof from Teacher where depart=\'电子工程系\' ))
select prof from Teacher where depart = \'计算机系\' and prof not in(select prof from Teacher where depart=\'电子工程系\' ) union
select prof from Teacher where depart = \'电子工程系\' and prof not in(select prof from Teacher where depart=\'计算机系\' )
29.一脸懵b中
答案：select * from Score where Cno=\'3-105\' and Degree>any(select Degree from Score where Cno =\'3-245\') order by Degree desc
30.select * from score where cno=\'3-105\' and degree>all(select degree from score where cno =\'3-245\')
31.select sname,ssex,sbirthday from student
union
select tname,tsex,tbirthday from teacher
32.select sname,ssex,sbirthday from student where ssex=\'女\'
union
select tname,tsex,tbirthday from teacher where tsex=\'女\'
33.select * from score a where degree<(select avg(degree) from score b where b.cno = a.cno)
34.我的答案：select tname,depart from teacher
答案：select Tname,depart from Teacher where Tno in (select Tno from Course )
结果是一样的
35.这个题脑子直接想不明白...
答案：select Tname,depart from Teacher where Tno in(select Tno from Course where Cno not in(select Cno from Score))
36.select class from student where ssex=\'男\' group by class having count(*)>1
37.select * from student where sno not in(select sno from student where sname like \'王%\')
38.select Sname,YEAR(now())-YEAR(Sbirthday) from Student
不知道为什么我写的运行不出来 我没写year
39.select max(sbirthday) from student
select min(sbirthday) from student
40.select * from student order by class desc,sbirthday
41.脑子要炸了
答案：select * from Teacher join Course on Teacher.Tno = Course.Tno where Teacher.Tsex=\'男\'
42.select * from score where degree = (select max(degree) from score )
43.select sname from student where ssex = (select ssex from student where sname=\'李军\')
44.加了个条件就弄不出来了...
答案：select Sname from Student where Ssex = (select Ssex from Student where Sname=\'李军\') and Class=(select Class from Student where Sname = \'李军\')
45.最后一题依旧写不出来
答案：select * from Score where Sno in(select Sno from Student where Ssex=\'男\') and Cno in(select Cno from Course where Cname=\'计算机导论\')

 

 

做完这45道题感觉脑子变得和浆糊一样   有三分之一写不出来的   甚至有的看答案都弄不明白不过感觉思路学到不少   就是高级查询一旦到了3层、4层就开始糊迷了   很多时候想

得到却写不出     看来还是too young too simple 还是缺练

另外感觉程序不能马虎啊   一点点问题  甚至一个分号  就会导致崩盘    要细心啊