MySQL45道面试题及答案-白红宇

MySQL45道面试题及答案
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发布时间：2019-06-23
本文共 8633 字，大约阅读时间需要 28 分钟。
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
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