SQL数据库面试题以及答案
Student(stuId,stuName,stuAge,stuSex) 学生表
stuId：学号；stuName：学生姓名；stuAge：学生年龄；stuSex：学生性别
Course(courseId,courseName,teacherId) 课程表
courseId,课程编号；courseName：课程名字；teacherId：教师编号
Scores(stuId,courseId,score) 成绩表
stuId：学号；courseId,课程编号；score：成绩
Teacher(teacherId,teacherName) 教师表
teacherId：教师编号； teacherName：教师名字
问题：
1、查询“001”课程比“002”课程成绩高的所有学生的学号；
select a.stuId from (select stuId,score from Scores where courseId='001') a,(select stuId,score
from Scores where courseId='002') b
where a.score>b.score and a.stuId=b.stuId;
2、查询平均成绩大于60分的同学的学号和平均成绩；
select stuId,avg(score)
from Scores
group by stuId having avg(score) >60;
3、查询所有同学的学号、姓名、选课数、总成绩；
select Student.stuId,Student.stuName,count(Scores.courseId),sum(score)
from Student left Outer join Scores on Student.stuId=Scores.stuId
group by Student.stuId,stuName
4、查询姓“李”的老师的个数；
select count(distinct(teacherName))
from Teacher
where teacherName like '李%';
5、查询没学过“叶平”老师课的同学的学号、姓名；
select Student.stuId,Student.stuName
from Student
where stuId not in (select distinct( Scores.stuId) from Scores,Course,Teacher where Scores.courseId=Course.courseId and Teacher.teacherId=Course.teacherId and Teacher.teacherName='叶平');
6、查询学过“001”并且也学过编号“002”课程的同学的学号、姓名；
select Student.stuId,Student.stuName from Student,Scores where Student.stuId=Scores.stuId and Scores.courseId='001'and exists( Select * from Scores as Scores_2 where Scores_2.stuId=Scores.stuId and Scores_2.courseId='002');
7、查询学过“叶平”老师所教的所有课的同学的学号、姓名；
select stuId,stuName
from Student
where stuId in (select stuId from Scores ,Course ,Teacher where Scores.courseId=Course.courseId and Teacher.teacherId=Course.teacherId and Teacher.teacherName='叶平' group by stuId having count(Scores.courseId)=(select count(courseId) from Course,Teacher where Teacher.teacherId=Course.teacherId and teacherName='叶平'));
8、查询课程编号“002”的成绩比课程编号“001”课程低的所有同学的学号、姓名；
Select stuId,stuName from (select Student.stuId,Student.stuName,score ,(select score from Scores Scores_2 where Scores_2.stuId=Student.stuId and Scores_2.courseId='002') score2
from Student,Scores where Student.stuId=Scores.stuId and courseId='001') S_2 where score2 <score;
9、查询所有课程成绩小于60分的同学的学号、姓名；
select stuId,stuName
from Student
where stuId not in (select Student.stuId from Student,Scores where S.stuId=Scores.stuId and score>60);
10、查询没有学全所有课的同学的学号、姓名；
select Student.stuId,Student.stuName
from Student,Scores
where Student.stuId=Scores.stuId group by Student.stuId,Student.stuName having count(courseId) <(select count(courseId) from Course);
11、查询至少有一门课与学号为“1001”的同学所学相同的同学的学号和姓名；
select stuId,stuName from Student,Scores where Student.stuId=Scores.stuId and courseId in select courseId from Scores where stuId='1001';
12、查询至少学过学号为“001”同学所有一门课的其他同学学号和姓名；
select distinct Scores.stuId,stuName
from Student,Scores
where Student.stuId=Scores.stuId and courseId in (select courseId from Scores where stuId='001');
13、把“Scores”表中“叶平”老师教的课的成绩都更改为此课程的平均成绩；
update Scores set score=(select avg(Scores_2.score)
from Scores Scores_2
where Scores_2.courseId=Scores.courseId ) from Course,Teacher where Course.courseId=Scores.courseId and Course.teacherId=Teacher.teacherId and Teacher.teacherName='叶平');
14、查询和“1002”号的同学学习的课程完全相同的其他同学学号和姓名；
select stuId from Scores where courseId in (select courseId from Scores where stuId='1002')
group by stuId having count(*)=(select count(*) from Scores where stuId='1002');
15、删除学习“叶平”老师课的Scores表记录；
Delect Scores
from course ,Teacher
where Course.courseId=Scores.courseId and Course.teacherId= Teacher.teacherId and teacherName='叶平';
16、向Scores表中插入一些记录，这些记录要求符合以下条件：没有上过编号“003”课程的同学学号、2、
号课的平均成绩；
Insert Scores select stuId,'002',(Select avg(score)
from Scores where courseId='002') from Student where stuId not in (Select stuId from Scores where courseId='002');
17、按平均成绩从高到低显示所有学生的“数据库”、“企业管理”、“英语”三门的课程成绩，按如下形式显示： 学生ID,,数据库,企业管理,英语,有效课程数,有效平均分
SELECT stuId as 学生ID
,(SELECT score FROM Scores WHERE Scores.stuId=t.stuId AND courseId='004') AS 数据库
,(SELECT score FROM Scores WHERE Scores.stuId=t.stuId AND courseId='001') AS 企业管理
,(SELECT score FROM Scores WHERE Scores.stuId=t.stuId AND courseId='006') AS 英语
,COUNT(*) AS 有效课程数, AVG(t.score) AS 平均成绩
FROM Scores AS t
GROUP BY stuId
ORDER BY avg(t.score)
18、查询各科成绩最高和最低的分：以如下形式显示：课程ID，最高分，最低分
SELECT L.courseId As 课程ID,L.score AS 最高分,R.score AS 最低分
FROM Scores L ,Scores AS R
WHERE L.courseId = R.courseId and
L.score = (SELECT MAX(IL.score)
FROM Scores AS IL,Student AS IM
WHERE L.courseId = IL.courseId and IM.stuId=IL.stuId
GROUP BY IL.courseId)
AND
R.score = (SELECT MIN(IR.score)
FROM Scores AS IR
WHERE R.courseId = IR.courseId
GROUP BY IR.courseId
);
19、按各科平均成绩从低到高和及格率的百分数从高到低顺序
SELECT t.courseId AS 课程号,max(course.courseName)AS 课程名,isnull(AVG(score),0) AS 平均成绩
,100 * SUM(CASE WHEN isnull(score,0)>=60 THEN 1 ELSE 0 END)/COUNT(*) AS 及格百分数
FROM Scores T,Course
where t.courseId=course.courseId
GROUP BY t.courseId
ORDER BY 100 * SUM(CASE WHEN isnull(score,0)>=60 THEN 1 ELSE 0 END)/COUNT(*) DEScores
20、查询如下课程平均成绩和及格率的百分数(用"1行"显示): 企业管理（001），马克思（002），OO&UML （003），数据库（004）
SELECT SUM(CASE WHEN courseId ='001' THEN score ELSE 0 END)/SUM(CASE courseId WHEN '001' THEN 1 ELSE 0 END) AS 企业管理平均分
,100 * SUM(CASE WHEN courseId = '001' AND score >= 60 THEN 1 ELSE 0 END)/SUM(CASE WHEN courseId = '001' THEN 1 ELSE 0 END) AS 企业管理及格百分数
,SUM(CASE WHEN courseId = '002' THEN score ELSE 0 END)/SUM(CASE courseId WHEN '002' THEN 1 ELSE 0 END) AS 马克思平均分
,100 * SUM(CASE WHEN courseId = '002' AND score >= 60 THEN 1 ELSE 0 END)/SUM(CASE WHEN courseId = '002' THEN 1 ELSE 0 END) AS 马克思及格百分数
,SUM(CASE WHEN courseId = '003' THEN score ELSE 0 END)/SUM(CASE courseId WHEN '003' THEN 1 ELSE 0 END) AS UML平均分
,100 * SUM(CASE WHEN courseId = '003' AND score >= 60 THEN 1 ELSE 0 END)/SUM(CASE WHEN courseId = '003' THEN 1 ELSE 0 END) AS UML及格百分数
,SUM(CASE WHEN courseId = '004' THEN score ELSE 0 END)/SUM(CASE courseId WHEN '004' THEN 1 ELSE 0 END) AS 数据库平均分
,100 * SUM(CASE WHEN courseId = '004' AND score >= 60 THEN 1 ELSE 0 END)/SUM(CASE WHEN courseId = '004' THEN 1 ELSE 0 END) AS 数据库及格百分数
FROM Scores
21、查询不同老师所教不同课程平均分从高到低显示
SELECT max(Z.teacherId) AS 教师ID,MAX(Z.teacherName) AS 教师姓名,C.courseId AS 课程ＩＤ,MAX(C.courseName) AS 课程名称,AVG(score) AS 平均成绩
FROM Scores AS T,Course AS C ,Teacher AS Z
where T.courseId=C.courseId and C.teacherId=Z.teacherId
GROUP BY C.courseId
ORDER BY AVG(score) DEScores
22、查询如下课程成绩第 3 名到第 6 名的学生成绩单：企业管理（001），马克思（002），UML （003），数据库（004）
[学生ID],[学生姓名],企业管理,马克思,UML,数据库,平均成绩
SELECT DISTINCT top 3
Scores.stuId As 学生学号,
Student.stuName AS 学生姓名 ,
T1.score AS 企业管理,
T2.score AS 马克思,
T3.score AS UML,
T4.score AS 数据库,
ISNULL(T1.score,0) + ISNULL(T2.score,0) + ISNULL(T3.score,0) + ISNULL(T4.score,0) as 总分
FROM Student,Scores LEFT JOIN Scores AS T1
ON Scores.stuId = T1.stuId AND T1.courseId = '001'
LEFT JOIN Scores AS T2
ON Scores.stuId = T2.stuId AND T2.courseId = '002'
LEFT JOIN Scores AS T3
ON Scores.stuId = T3.stuId AND T3.courseId = '003'
LEFT JOIN Scores AS T4
ON Scores.stuId = T4.stuId AND T4.courseId = '004'
WHERE student.stuId=Scores.stuId and
ISNULL(T1.score,0) + ISNULL(T2.score,0) + ISNULL(T3.score,0) + ISNULL(T4.score,0)
NOT IN
(SELECT
DISTINCT
TOP 15 WITH TIES
ISNULL(T1.score,0) + ISNULL(T2.score,0) + ISNULL(T3.score,0) + ISNULL(T4.score,0)
FROM Scores
LEFT JOIN Scores AS T1
ON Scores.stuId = T1.stuId AND T1.courseId = 'k1'
LEFT JOIN Scores AS T2
ON Scores.stuId = T2.stuId AND T2.courseId = 'k2'
LEFT JOIN Scores AS T3
ON Scores.stuId = T3.stuId AND T3.courseId = 'k3'
LEFT JOIN Scores AS T4
ON Scores.stuId = T4.stuId AND T4.courseId = 'k4'
ORDER BY ISNULL(T1.score,0) + ISNULL(T2.score,0) + ISNULL(T3.score,0) + ISNULL(T4.score,0) DEScores);
23、统计列印各科成绩,各分数段人数:课程ID,课程名称,[100-85],[85-70],[70-60],[ <60]
SELECT Scores.courseId as 课程ID, courseName as 课程名称
,SUM(CASE WHEN score BETWEEN 85 AND 100 THEN 1 ELSE 0 END) AS [100 - 85]
,SUM(CASE WHEN score BETWEEN 70 AND 85 THEN 1 ELSE 0 END) AS [85 - 70]
,SUM(CASE WHEN score BETWEEN 60 AND 70 THEN 1 ELSE 0 END) AS [70 - 60]
,SUM(CASE WHEN score < 60 THEN 1 ELSE 0 END) AS [60 -]
FROM Scores,Course
where Scores.courseId=Course.courseId
GROUP BY Scores.courseId,courseName;
24、查询学生平均成绩及其名次
SELECT 1+(SELECT COUNT( distinct 平均成绩)
FROM (SELECT stuId,AVG(score) AS 平均成绩
FROM Scores
GROUP BY stuId
) AS T1
WHERE 平均成绩 > T2.平均成绩) as 名次,
stuId as 学生学号,平均成绩
FROM (SELECT stuId,AVG(score) 平均成绩
FROM Scores
GROUP BY stuId
) AS T2
ORDER BY 平均成绩 deScores;
25、查询各科成绩前三名的记录:(不考虑成绩并列情况)
SELECT t1.stuId as 学生ID,t1.courseId as 课程ID,score as 分数
FROM Scores t1
WHERE score IN (SELECT TOP 3 score
FROM Scores
WHERE t1.courseId= courseId
ORDER BY score DEScores
)
ORDER BY t1.courseId;
26、查询每门课程被选修的学生数
select courseId,count(stuId) from Scores group by courseId;
27、查询出只选修了一门课程的全部学生的学号和姓名
select Scores.stuId,Student.stuName,count(courseId) AS 选课数
from Scores ,Student
where Scores.stuId=Student.stuId group by Scores.stuId ,Student.stuName having count(courseId)=1;
28、查询男生、女生人数
Select count(stuSex) as 男生人数 from Student group by stuSex having stuSex='男';
Select count(stuSex) as 女生人数 from Student group by stuSex having stuSex='女'；
29、查询姓“张”的学生名单
SELECT stuName FROM Student WHERE stuName like '张%';
30、查询同名同性学生名单，并统计同名人数
select stuName,count(*) from Student group by stuName having count(*)>1;;
31、1981年出生的学生名单(注：Student表中stuAge列的类型是datetime)
select stuName, CONVERT(char (11),DATEPART(year,stuAge)) as age
from student
where CONVERT(char(11),DATEPART(year,stuAge))='1981';
32、查询每门课程的平均成绩，结果按平均成绩升序排列，平均成绩相同时，按课程号降序排列
Select courseId,Avg(score) from Scores group by courseId order by Avg(score),courseId DEScores ;
33、查询平均成绩大于85的所有学生的学号、姓名和平均成绩
select stuName,Scores.stuId ,avg(score)
from Student,Scores
where Student.stuId=Scores.stuId group by Scores.stuId,stuName having avg(score)>85;
34、查询课程名称为“数据库”，且分数低于60的学生姓名和分数
Select stuName,isnull(score,0)
from Student,Scores,Course
where Scores.stuId=Student.stuId and Scores.courseId=Course.courseId and Course.courseName='数据库'and score <60;
35、查询所有学生的选课情况；
SELECT Scores.stuId,Scores.courseId,stuName,courseName
FROM Scores,Student,Course
where Scores.stuId=Student.stuId and Scores.courseId=Course.courseId ;
36、查询任何一门课程成绩在70分以上的姓名、课程名称和分数；
SELECT distinct student.stuId,student.stuName,Scores.courseId,Scores.score
FROM student,Scores
WHERE Scores.score>=70 AND Scores.stuId=student.stuId;
37、查询不及格的课程，并按课程号从大到小排列
select courseId from Scores where Scoresor e <60 order by courseId ;
38、查询课程编号为003且课程成绩在80分以上的学生的学号和姓名；
select Scores.stuId,Student.stuName from Scores,Student where Scores.stuId=Student.stuId and score>80 and courseId='003';
39、求选了课程的学生人数
select count(*) from Scores;
40、查询选修“叶平”老师所授课程的学生中，成绩最高的学生姓名及其成绩
select Student.stuName,score
from Student,Scores,Course C,Teacher
where Student.stuId=Scores.stuId and Scores.courseId=C.courseId and C.teacherId=Teacher.teacherId and Teacher.teacherName='叶平' and Scores.score=(select max(score)from Scores where courseId=C.courseId );
41、查询各个课程及相应的选修人数
select count(*) from Scores group by courseId;
42、查询不同课程成绩相同的学生的学号、课程号、学生成绩
select distinct A.stuId,B.score from Scores A ,Scores B where A.score=B.score and A.courseId <>B.courseId ;
43、查询每门功成绩最好的前两名
SELECT t1.stuId as 学生ID,t1.courseId as 课程ID,score as 分数
FROM Scores t1
WHERE score IN (SELECT TOP 2 score
FROM Scores
WHERE t1.courseId= courseId
ORDER BY score DEScores
)
ORDER BY t1.courseId;
44、统计每门课程的学生选修人数（超过10人的课程才统计）。要求输出课程号和选修人数，查询结果按人数降序排列，查询结果按人数降序排列，若人数相同，按课程号升序排列
select courseId as 课程号,count(*) as 人数
from Scores
group by courseId
order by count(*) deScores,courseId
45、检索至少选修两门课程的学生学号
select stuId
from Scores
group by stuId
having count(*) > = 2
46、查询全部学生都选修的课程的课程号和课程名
select courseId,courseName
from Course
where courseId in (select courseId from Scores group by courseId)
47、查询没学过“叶平”老师讲授的任一门课程的学生姓名
select stuName from Student where stuId not in (select stuId from Course,Teacher,Scores where Course.teacherId=Teacher.teacherId and Scores.courseId=course.courseId and teacherName='叶平');
48、查询两门以上不及格课程的同学的学号及其平均成绩
select stuId,avg(isnull(score,0)) from Scores where stuId in (select stuId from Scores where score <60 group by stuId having count(*)>2)group by stuId;
49、检索“004”课程分数小于60，按分数降序排列的同学学号
select stuId from Scores where courseId='004'and score <60 order by score deScores;
50、删除“002”同学的“001”课程的成绩
delete from Scores where stuId='002'and courseId='001';
