MySQL45道面试题及答案

create database  school;use school;

#学生表create table `Student`(  `Sno` varchar(20) not null COMMENT ‘人名‘,  `Sname` varchar(20) not null COMMENT ‘姓名‘,  `Ssex` varchar(20) not null COMMENT ‘性别‘,  `Sbirthday` datetime COMMENT ‘出生日期‘,  `Class` varchar(20) COMMENT ‘班级‘);#课程表create table `Course`(  `Cno` varchar(20) not null COMMENT ‘课程号‘,  `Cname` varchar(20) not null COMMENT ‘课程名称‘,  `Tno` varchar(20) not null COMMENT ‘教工编号‘);#成绩表Create table `Score` (  `Sno` varchar(20) not null COMMENT ‘学号‘,  `Cno` varchar(20) not NULL comment ‘课程号‘,  `Degree` DECIMAL(4,1) null COMMENT ‘成绩‘);#教师表create table `Teacher` (  `Tno` varchar(20) not null COMMENT ‘教工编号‘,  `Tname` varchar(20) not null COMMENT ‘教工姓名‘,  `Tsex` varchar(20) not null COMMENT ‘教工性别‘,  `Tbirthday` datetime null COMMENT ‘教工出生日期‘,  `Prof` varchar(20) null COMMENT ‘职称‘,  `Depart` varchar(20) null COMMENT ‘教工所在部门‘);

insert into `Student` value(108,‘曾华‘,‘男‘,‘1977-09-01‘,95033),(105,‘匡明‘,‘男‘,‘1975-10-02‘,95031),(107,‘王丽‘,‘女‘,‘1976-01-23‘,95033),(101,‘李军‘,‘男‘,‘1976-02-20‘,95033),(109,‘王芳‘,‘女‘,‘1975-02-10‘,95031),(103,‘陆军‘,‘男‘,‘1974-06-03‘,95031);

insert into `Course` value(3-105,‘计算机导论‘,825),(3-245,‘操作系统‘,804),(6-166,‘数字电路‘,856),(9-888,‘高等数学‘,831);

insert into `Score` value(103,3-245,86),(105,3-245,75),(109,3-245,68),(103,3-105,92),(105,3-105,88),(109,3-105,76),(101,2-105,64),(107,3-105,91),(108,3-105,78),(101,6-166,85),(107,6-166,79),(108,6-166,81);

insert into `Teacher` value(804,‘李城‘,‘男‘,‘1958-12-02‘,‘副教授‘,‘计算机系‘),(856,‘张旭‘,‘男‘,‘1969-03-12‘,‘讲师‘,‘电子工程系‘),(825,‘王萍‘,‘女‘,‘1972-05-05‘,‘助教‘,‘计算机系‘),(831,‘刘冰‘,‘女‘,‘1977-08-14‘,‘助教‘,‘电子工程系‘);

#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。（多练）select distinct Depart from `Teacher`;

-- 第三题 查询Student表的所有记录。select * from `Student`;

-- 第四题 查询Score表中成绩在60到80之间的所有记录。select * from `Score` where Degree >60 and Degree<80;select * from `Score` where Degree between 60 and 80;

-- 第五题 查询Score表中成绩为85，86或88的记录。select * from `Score` where Degree = 85  or Degree =  86 or  Degree =  88;select * from `Score` where Degree in(85,86,88);

-- 第六题 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‘;

-- 第七题 以Class降序查询Student表的所有记录。select * from `Student` order by Class desc;

-- 第八题 以Cno升序、Degree降序查询Score表的所有记录。select * from `Score` order by Cno asc,Degree desc ;

-- 第九题 查询“95031”班的学生人数。select count(*) from `Student` where Class = ‘95031‘;

-- 第十题 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 from `Score` where Degree=(select Max(Degree) from Score);select Sno,Cno from `Score` order by Degree desc;

-- 第十一题 查询每门课的平均成绩。(group by:根据Cno进行分组)select Cno,AVG(Degree) as 平均分 from `Score` group by Cno;

-- 第十二题 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 * from `Score` where Cno like ‘3%‘ group by Cno having Count(Cno)>4;

-- 第十三题 查询分数大于70，小于90的Sno列。select Sno from `Score` where Degree>70 or Degree<90;select Sno from `Score` where Degree between 70 and 90;

-- 第十四题 查询所有学生的Sname、Cno和Degree列。select Sname,Cno from `Student` join `Score` on `Student`.Sno = `Score`.Sno;

-- 第十五题 查询所有学生的Sno、Cname和Degree列。select Sno,Cname,Degree from Score join Course on Course.Cno = Score.Cno;

-- 第十六题 查询所有学生的Sname、Cname和Degree列。select Sname,Cname,Degree from `Student` join Score on`Student`.Sno = `Score`.Sno join Course on `Course`.Cno = `Score`.Sno;

-- 第十七题 查询“95033”班学生的平均分。(子查询or条件查询)select AVG(Degree) from  `Score` where Sno in(select Sno from `Student` where Class=‘95033‘);

select Avg(Degree) from `Score`,Student where Student.Sno = Score.Sno and Class = ‘95033‘;

-- 第十八题 假设使用如下命令建立了一个grade表：create table `grede`(  `low` int   COMMENT ‘人名‘,  `upp` int not null COMMENT ‘课长‘,  `rank` varchar(20) not null COMMENT ‘等级‘);insert into `grede` values(90,100,‘A‘);insert into `grede` values(80,89,‘B‘);insert into `grede` values(70,79,‘C‘);insert into `grede` values(60,69,‘D‘);insert into `grede` values(0,59,‘E‘);

-- 现查询所有同学的Sno、Cno和rank列。(between选取两个值之间的数据范围)select Sno,Cno,Degree,rank from grede join Score on Score.Degree between    low and upp;

select Sno,Cno,Degree,rank from  Score,grede where Degree between    low and upp;

-- 第十九题 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 Score.Cno = ‘3-105‘ and Student.Sno = Score.Snoand Score.Degree>(select Degree from Score where Cno = ‘3-105‘ and Sno = ‘109‘);

-- 第二十题 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。select * from Score a where Degree<(select MAX(Degree)from  Score bwhere a.Cno = b.Cno) and Sno in(select Sno from Score group by  Sno having  count(*) > 1);

-- 第二十一题 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 Student,Score where Student.Sno = Score.Sno and Score.Degree>(select Degree from Score where Cno=‘3-105‘ and Sno = ‘109‘);

-- 第二十二题 查询和学号为107的同学同年出生的所有学生的Sno、Sname和Sbirthday列。select Sno,Sname,Sbirthday from student where year(Student.Sbirthday) = (    select year(Sbirthday) from student where Sno = ‘107‘    );

-- 第二十三题 查询“张旭“教师任课的学生成绩select Sno,Cno,Degree from Score where Cno in(select Cno from Course where   Tno in(select Tno from Teacher where Tname = ‘张旭‘));

-- 第二十四题 查询选修某课程的同学人数多于5人的教师姓名。select Tname from Teacher where Tno in(select Tno from Course where Cno in(select Cno from Scoregroup by Cno having Count(*)>5));

-- 第二十五题 查询95033班和95031班全体学生的记录。select * from Student where Class = ‘95033‘ or Class = ‘95031‘;

-- 第二十六题 查询存在有85分以上成绩的课程Cno.select distinct cno from Score where Degree>85;

-- 第二十七题 查询出“计算机系“教师所教课程的成绩表。select Sno,Cno,Degree from Score where Cno in(select Cno from Course where Tno in(    select tno from Teacher where Depart = ‘计算机系‘    ));

-- 第二十八题查询“计算机系”与“电子工程系“不同职称的教师的Tname和Prof。使用相关子查询select Tname,Prof from Teacher a where Prof not in(select Prof from Teacher b wherea.Depart!=b.Depart);

-- 第二十九题 查询选修编号为“3-105“课程且成绩至少高于选修编号为“3-245”课程的同学的Cno、Sno和Degree,并按Degree从高到低次序排序。select Cno,Sno,Degree from Score a where (select Degree from Score b where Cno=‘3-105‘ andb.Sno = a.Sno)>=(select Degree from Score c where Cno=‘3-245‘ and c.Sno = a.Sno)order byDegree desc ;

-- 第三十题 查询选修编号为“3-105”课程且成绩高于选修编号为“3-245”课程的同学的Cno、Sno和Degree.select Cno,Sno,Degree from Score a where (select Degree from Score b where Cno=‘3-105‘ andb.Sno=a.Sno)>(select Degree from Score c where Cno=‘3-245‘ and c.Sno=a.Sno);

-- 第三十一题 查询所有教师和同学的name、sex和birthday.select distinct Sname as name,Ssex as sex,Sbirthday as birthday from studentunionselect distinct Tname as name,Tsex as sex,Tbirthday as birthday from Teacher;

-- 第三十二题 查询所有“女”教师和“女”同学的name、sex和birthday.select distinct Sname as name,Ssex as sex,Sbirthday as birthday from student where Ssex = ‘女‘unionselect distinct Tname as name,Tsex as sex,Tbirthday as birthday from Teacher where Tsex = ‘女‘;

-- 第三十三题 查询成绩比该课程平均成绩低的同学的成绩表。select Sno,Cno,Degree from Score a where  a.Degree<(select AVG(Degree) from Score b where a.Cno = b.Cno);

-- 第三十四题 查询所有任课教师的Tname和Depart.select Tname,Depart from Teacher where Tname in(select distinct Tname from Teacher,Course,Score where Teacher.Tno = Course.Tno and Course.Cno = Score.Cno);

select Tname,Depart from Teacher where tno in (select tno from course where Cno in (select distinct Cno from Score));

-- 第三十五题 查询所有未讲课的教师的Tname和Depart.select Tname,Depart from Teacher where Tname not in(select distinct Tname from Teacher,Course,Score where Teacher.Tno=Course.Tno and Course.Cno = Score.Cno);

-- 第三十六题 查询至少有2名男生的班号。select Class from student where Ssex=‘男‘ group by Class having count(*)>1;

-- 第三十七题 查询Student表中不姓“王”的同学记录。select * from Student where Sname not like (‘王%‘);

-- 第三十八题 查询Student表中每个学生的姓名和年龄。select Sname,YEAR(GETDATE())-year(Sbirthday) from student;

-- 第三十九题 查询Student表中最大和最小的Sbirthday日期值select MAX(Sbirthday) as 最大,MIN(Sbirthday) as 最小 from student;

-- 第四十题 以班号和年龄从大到小的顺序查询Student表中的全部记录select * from Student order by Class desc ,Sbirthday asc;

-- 第四十一题 查询“男”教师及其所上的课程。select Tname,Cname from Teacher,Course where Tsex=‘男‘ and Teacher.Tno = Course.Tno;

-- 第四十二题 查询最高分同学的Sno、Cno和Degree列。select Sno,Cno,Degree from Score where Degree=(select MAX(Degree) FROM score);

-- 第四十三题 查询和“李军”同性别的所有同学的Sname.select SName from Student where Ssex=(select Ssex from Student where Sname=‘李军‘)and Snamenot in (‘李军‘);

-- 第四十四题 查询和“李军”同性别并同班的同学Snameselect Sname from Student where Ssex=(select Ssex from Student where Sname=‘李军‘)and Sname not in(‘李军‘)and Class=(select Class from Student where Sname=‘李军‘);

-- 第四十五题 查询所有选修“计算机导论”课程的“男”同学的成绩表select Sno,Degree 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‘);

原文地址：https://www.cnblogs.com/cheng88/p/10585715.html