mysql⼦查询练习建表以及数据
#建学⽣信息表student
CREATE TABLE student (
sno VARCHAR (20) NOT NULL PRIMARY KEY,
sname VARCHAR (20) NOT NULL,
ssex VARCHAR (20) NOT NULL,
sbirthday datetime,
class VARCHAR (20)
);
#建⽴教师表
create table teacher
(
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
);
#建⽴课程表course
create 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)
);
#建⽴成绩表
create table score
(
sno varchar(20) not null,
foreign key(sno) references student(sno),
cno varchar(20) not null,
foreign key(cno) references course(cno),
degree decimal
);
#添加学⽣信息
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');
#添加教师表
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');
#添加课程表
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');
#添加成绩表
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');
题⽬以及答案
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
mysql group by order bySELECT 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 degree FROM score WHERE degree >= 60 and degree ⇐80;
SELECT degree 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 degree 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(sno) From student WHERE class = "95031";
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 * from score order by degree DESC limit 1;
11、查询每门课的平均成绩。
SELECT cno,AVG(degree) FROM score GROUP BY cno;
13、查询分数⼤于70，⼩于90的Sno列。
SELECT * FROM score WHERE degree BETWEEN 70 AND 90;
14、查询所有学⽣的Sname、Cno和Degree列。
SELECT s.sname,sco,sc.degree FROM student s LEFT JOIN score sc on s.sno = sc.sno;
25、查询95033班和95031班全体学⽣的记录。
SELECT * FROM student where class in ("95033", "95031");
26、查询存在有85分以上成绩的课程Cno.
SELECT cno FROM score where degree > 85;
⼦查询连表查询
查询没有选修操作系统所有学⽣信息
select * from score where cno NOT IN (select cno from course where cname = '操作系统');
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 * from score where degree = (select max(degree) from score);
17、查询“95033”班学⽣的平均分。
select avg(degree) from score where sno IN (select sno from student where class = 95031);
12、查询Score表中⾄少有5名学⽣选修的课程的平均分数。
SELECT avg(degree) FROM score WHERE cno in (SELECT cno FROM score GROUP BY cno HAVING COUNT(sno) >= 5);
17、查询“95031”班学⽣的平均分。
select avg(degree) from score where sno IN (select sno from student where class = '95031');
23、查询“张旭“教师任课的学⽣成绩。
select * from score where cno = (select cno from course where tno = (select tno from teacher where tname = '张旭'));
24、查询选修某课程的同学⼈数多于5⼈的教师姓名。
select * from teacher where tno = (select tno from course where cno = (select cno from score group by cno having count(cno) > 5));
19、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 sno,degree FROM score WHERE cno = "3-105" and degree > ANY(SELECT degree FROM score sc WHERE sc.sno = "109" and sco = "3-105")；查询男⽼师所授课程所有学⽣的成绩
select * from score where cno = ANY(select cno from course where tno = ANY(select tno from teacher where tsex = '男'));
查询不上王萍⽼师课的所有学⽣信息
select * from score where cno != (select cno from course where tno = (select tno from teacher where tname = '王萍'));

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