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 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 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,sc.cno,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 sc.cno = "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'));
