mysql笔试题写sql语句_数据库MySQL经典⾯试题之SQL语句需要数据库表1.学⽣表
Student(SID,Sname,Sage,Ssex) --SID 学⽣编号,Sname 学⽣姓名,Sage 出⽣年⽉,Ssex 学⽣性别
2.课程表
Course(CID,Cname,TID) --CID --课程编号,Cname 课程名称,TID 教师编号
3.教师表
Teacher(TID,Tname) --TID 教师编号,Tname 教师姓名
4.成绩表
SC(SID,CID,score) --SID 学⽣编号,CID 课程编号,score 分数
添加测试数据1.学⽣表
create table Student(SID varchar(10),Sname nvarchar(10),Sage datetime,Ssex nvarchar(10));
insert into Student values('01' , '赵雷' , '1990-01-01' , '男');
insert into Student values('02' , '钱电' , '1990-12-21' , '男');
insert into Student values('03' , '孙风' , '1990-05-20' , '男');
insert into Student values('04' , '李云' , '1990-08-06' , '男');
insert into Student values('05' , '周梅' , '1991-12-01' , '⼥');
insert into Student values('06' , '吴兰' , '1992-03-01' , '⼥');
insert into Student values('07' , '郑⽵' , '1989-07-01' , '⼥');
insert into Student values('08' , '王菊' , '1990-01-20' , '⼥');
2.课程表
create table Course(CID varchar(10),Cname nvarchar(10),TID varchar(10));
insert into Course values('01' , '语⽂' , '02');
insert into Course values('02' , '数学' , '01');
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insert into Course values('03' , '英语' , '03');
3.教师表
create table Teacher(TID varchar(10),Tname nvarchar(10));
insert into Teacher values('01' , '张三');
insert into Teacher values('02' , '李四');
insert into Teacher values('03' , '王五');
4.成绩表
create table SC(SID varchar(10),CID varchar(10),score decimal(18,1));
insert into SC values('01' , '01' , 80);
insert into SC values('01' , '02' , 90);
insert into SC values('01' , '03' , 99);
insert into SC values('02' , '01' , 70);
insert into SC values('02' , '02' , 60);
insert into SC values('02' , '03' , 80);
insert into SC values('03' , '01' , 80);
insert into SC values('03' , '02' , 80);
insert into SC values('03' , '03' , 80);
insert into SC values('04' , '01' , 50);
insert into SC values('04' , '02' , 30);
insert into SC values('04' , '03' , 20);
insert into SC values('05' , '01' , 76);
insert into SC values('05' , '02' , 87);
insert into SC values('06' , '01' , 31);
insert into SC values('06' , '03' , 34);
insert into SC values('07' , '02' , 89);
insert into SC values('07' , '03' , 98);
--1、查询"01"课程⽐"02"课程成绩⾼的学⽣的信息及课程分数--1.1、查询同时存在"01"课程和"02"课程的情况
select a.* , b.score 课程01的分数,c.score 课程02的分数 from Student a , SC b , SC c
where a.SID = b.SID and a.SID = c.SID and b.CID = '01' and c.CID = '02' and b.score > c.score
--1.2、查询同时存在"01"课程和"02"课程的情况和存在"01"课程但可能不存在"02"课程的情况(不存在时显⽰为null)(以下存在相同内容时不再解释)
select a.* , b.score 课程01的分数,c.score 课程02的分数 from Student a
left join SC b on a.SID = b.SID and b.CID = '01'
多态性位点指数left join SC c on a.SID = c.SID and c.CID = '02'js unicode编码转换中文
where b.score > isnull(c.score)
--2、查询"01"课程⽐"02"课程成绩低的学⽣的信息及课程分数--2.1、查询同时存在"01"课程和"02"课程的情况
select a.* , b.score 课程01的分数 ,c.score 课程02的分数 from Student a , SC b , SC c
where a.SID = b.SID and a.SID = c.SID and b.CID = '01' and c.CID = '02' and b.score < c.score
--2.2、查询同时存在"01"课程和"02"课程的情况和不存在"01"课程但存在"02"课程的情况
select a.* , b.score 课程01的分数 ,c.score 课程02的分数 from Student a
left join SC b on a.SID = b.SID and b.CID = '01'
left join SC c on a.SID = c.SID and c.CID = '02'
where isnull(b.score,0) < c.score
--3、查询平均成绩⼤于等于60分的同学的学⽣编号和学⽣姓名和平均成绩
select a.SID , a.Sname , cast(avg(b.score) as decimal(18,2)) avg_score
from Student a , sc b
where a.SID = b.SID
group by a.SID , a.Sname
having cast(avg(b.score) as decimal(18,2)) >= 60
order by a.SID
--4、查询平均成绩⼩于60分的同学的学⽣编号和学⽣姓名和平均成绩--4.1、查询在sc表存在成绩的学⽣信息的SQL语句。select a.SID , a.Sname , cast(avg(b.score) as decimal(18,2)) avg_score
from Student a , sc b
where a.SID = b.SID
group by a.SID , a.Sname
having cast(avg(b.score) as decimal(18,2)) < 60
order by a.SID
--4.2、查询在sc表中不存在成绩的学⽣信息的SQL语句。
select a.SID , a.Sname , isnull(cast(avg(b.score) as decimal(18,2)),0) avg_score
from Student a left join sc b
on a.SID = b.SID
group by a.SID , a.Sname
having isnull(cast(avg(b.score) as decimal(18,2)),0) < 60
dede帝国采集功能order by a.SID
--5、查询所有同学的学⽣编号、学⽣姓名、选课总数、所有课程的总成绩--5.1、查询所有有成绩的SQL。
select a.SID 学⽣编号 , a.Sname 学⽣姓名 , count(b.CID) 选课总数, sum(score) 所有课程的总成绩
mysql怎么读英语from Student a , SC b
where a.SID = b.SID
group by a.SID,a.Sname
order by a.SID
--5.2、查询所有(包括有成绩和⽆成绩)的SQL。
select a.SID 学⽣编号 , a.Sname 学⽣姓名 , count(b.CID) 选课总数, sum(score) 所有课程的总成绩
from Student a left join SC b
on a.SID = b.SID
group by a.SID,a.Sname
order by a.SID
--6、查询"李"姓⽼师的数量
--⽅法1
select count(Tname) 李姓⽼师的数量 from Teacher where Tname like '李%'
--⽅法2
select count(Tname) 李姓⽼师的数量 from Teacher where left(Tname,1) = '李'
--7、查询学过"张三"⽼师授课的同学的信息
select distinct Student.* from Student , SC , Course , Teacher
where Student.SID = SC.SID and SC.CID = Course.CID and Course.TID = Teacher.TID and Teacher.Tname = '张三'
建网站要先建什么order by Student.SID
--8、查询没学过"张三"⽼师授课的同学的信息
select m.* from Student m where SID not in (select distinct SC.SID from SC , Course , Teacher where SC.CID = Course.CID and Course.TID = Teacher.TID and Teacher.Tname = '张三') order by m.SID
-
-9、查询学过编号为"01"并且也学过编号为"02"的课程的同学的信息
--⽅法1
select Student.* from Student , SC where Student.SID = SC.SID and SC.CID = '01' and exists (Select 1 from SC SC_2 where SC_2.SID = SC.SID and SC_2.CID = '02') order by Student.SID
--⽅法2
select Student.* from Student , SC where Student.SID = SC.SID and SC.CID = '02' and exists (Select 1 from SC SC_2 where SC_2.SID = SC.SID and SC_2.CID = '01') order by Student.SID
--⽅法3
select m.* from Student m where SID in
(
select SID from
(
select distinct SID from SC where CID = '01'
union all
select distinct SID from SC where CID = '02'
) t group by SID having count(1) = 2
)
order by m.SID
--10、查询学过编号为"01"但是没有学过编号为"02"的课程的同学的信息
--⽅法1
select Student.* from Student , SC where Student.SID = SC.SID and SC.CID = '01' and not exists (Select 1 from SC SC_2 where SC_2.SID = SC.SID and SC_2.CID = '02') order by Student.SID
--⽅法2
select Student.* from Student , SC where Student.SID = SC.SID and SC.CID = '01' and Student.SID not in (Select SC_2.SID from SC SC_2 where SC_2.SID = SC.SID and SC_2.CID = '02') order by Student.SID
--11、查询没有学全所有课程的同学的信息
--11.1、
select Student.*
from Student , SC
where Student.SID = SC.SID
group by Student.SID , Student.Sname , Student.Sage , Student.Ssex having count(CID) < (select count(CID) from Course)
--11.2
select Student.*
from Student left join SC
on Student.SID = SC.SID
group by Student.SID , Student.Sname , Student.Sage , Student.Ssex having count(CID) < (select count(CID) from Course)
--12、查询⾄少有⼀门课与学号为"01"的同学所学相同的同学的信息
select distinct Student.* from Student , SC where Student.SID = SC.SID and SC.CID in (select CID from SC where SID = '01') and Student.SID <> '01'
--13、查询和"01"号的同学学习的课程完全相同的其他同学的信息
select Student.* from Student where SID in
(select distinct SC.SID from SC where SID <> '01' and SC.CID in (select distinct CID from SC where SID = '01')
group by SC.SID having count(1) = (select count(1) from SC where SID='01'))
-
-14、查询没学过"张三"⽼师讲授的任⼀门课程的学⽣姓名
select student.* from student where student.SID not in
(select distinct sc.SID from sc , course , teacher where sc.CID = course.CID and course.TID = teacher.TID ame = '张三')
order by student.SID
--15、查询两门及其以上不及格课程的同学的学号，姓名及其平均成绩
select student.SID , student.sname , cast(avg(score) as decimal(18,2)) avg_score from student , sc
where student.SID = SC.SID and student.SID in (select SID from SC where score < 60 group by SID having count(1) >= 2)
group by student.SID , student.sname
--16、检索"01"课程分数⼩于60，按分数降序排列的学⽣信息
select student.* , sc.CID , sc.score from student , sc
where student.SID = SC.SID and sc.score < 60 and sc.CID = '01'
order by sc.score desc
--17、按平均成绩从⾼到低显⽰所有学⽣的所有课程的成绩以及平均成绩--17.1 SQL 2000 静态
select a.SID 学⽣编号 , a.Sname 学⽣姓名 ,
max(case c.Cname when '语⽂' then b.score else null end) 语⽂ ,
max(case c.Cname when '数学' then b.score else null end) 数学 ,
max(case c.Cname when '英语' then b.score else null end) 英语 ,
cast(avg(b.score) as decimal(18,2)) 平均分
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