MySQL45道面试题及答案

旧城等待， 2021-12-23 16:41 301阅读 0赞

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.Sno
    and 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 b
    where 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 Score
    group 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 where
    a.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' and
    b.Sno = a.Sno)>=(select Degree from Score c where Cno='3-245' and c.Sno = a.Sno)order by
    Degree 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' and
    b.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 student
    union
    select 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'
    union
    select 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 Sname
    not in ('李军');
    
    -- 第四十四题 查询和“李军”同性别并同班的同学Sname
    select 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');

转载于:https://www.cnblogs.com/cheng88/p/10585715.html