数据库面试题以及答案50例题”>SQL数据库面试题以及答案(50例题)
Student(S#,Sname,Sage,Ssex)学生表 S#:学号 Sname:学生姓名 Sage:学生年龄 Ssex:学生性别 Course(C#,Cname,T#)课程表 C#:课程编号 Cname:课程名称 T#:教师编号 SC(S#,C#,score)成绩表 S#:学号 C#:课程编号 score:成绩 Teacher(T#,Tname)教师表 T#:教师编号: Tname: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.S# from (select S#,score from SC where C#='001')a, (select s#,score from SC where c#='002')b Where a.score>b.score and a.s# = b.s#;
2、查询平均成绩大于60分的同学的学号和平均成绩
select S#, avg(score) from sc group by S# having avg(score)>60
3、查询所有同学的学号、姓名、选课数、总成绩
select student.S#, student.Sname, count(sc.C#), sum(score) from student left outer join SC on student.S# = SC.S# group by Student.S#, Sname
4、查询姓‘李’的老师的个数:
select count(distinct(Tname)) from teacher where tname like '李%';
5、查询没有学过“叶平”老师可的同学的学号、姓名:
select student.S#, student.Sname from Student where S# not in (select distinct(SC.S#) from SC,Course,Teacher where sc.c#=course.c# AND teacher.T#=course.T# AND Teahcer.Tname ='叶平');
6、查询学过“叶平”老师所教的所有课的同学的学号、姓名:
select S#,Sname from Student where S# in (select S# from SC ,Course ,Teacher where SC.C#=Course.C# and Teacher.T#=Course.T# and Teacher.Tname='叶平' group by S# having count(SC.C#)=(select count(C#) from Course,Teacher where Teacher.T#=Course.T# and Tname='叶平'));
7、查询学过“011”并且也学过编号“002”课程的同学的学号、姓名:
select Student.S#,Student.Sname from Student,SC where Student.S#=SC.S# and SC.C#='001'and exists( Select * from SC as SC_2 where SC_2.S#=SC.S# and SC_2.C#='002');
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 S#,Sname from (select Student.S#,Student.Sname,score , (select score from SC SC_2 where SC_2.S#=Student.S# and SC_2.C#='002') score2 from Student,SC where Student.S#=SC.S# and C#='001') S_2 where score2 < score;
9、查询所有课程成绩小于60的同学的学号、姓名:
select S#, sname from student where s# not in (select student.s# from student, sc where s.s# = sc.s# and score>60);
10、查询没有学全所有课的同学的学号、姓名:
select student.s#, student.sname from student, sc where student.s#=sc.s# group by student.s#, student.sname having count(c#)<(select count(c#) from course);
11、查询至少有一门课与学号为“1001”同学所学相同的同学的学号和姓名:
select s#, Sname from Student, SC where student.s# = sc.s# and c# in (select c# from SC where s#='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 sc.s# , sname from student, sc where student.s#=sc.s# and c# in (select C# from sc where s#='001');
13、把“SC”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 Sc Set Score=(Select Avg(s2_Score) From sc s2 Where s2.c#=sc.c#) Where c# IN (Select c# From sc cs INNER JOIN Teacher tc ON cs.t#=tc.t# WHERE tname ='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 s# from sc where c# in (select c# from sc where s#='1002') group by s# having count(*)= (select count(*) from sc where s#='1002');
15、删除学习“叶平”老师课的SC表记录:
delect sc from course, Teacher where course.c#=sc.c# and course.t#=teacher.t# and tname='叶平';
16、向SC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、002号课的平均成绩:
Insert SC select S#,'002', (Select avg(score) from SC where C#='002') from Student where S# not in (Select S# from SC where C#='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 s# as 学生ID, (select score from sc where sc.s#=t.s# and c#='004') as 数据库, (select score from sc where sc.s#=t.s# and c#='001') as 企业管理, (select score from sc where sc.s#=t.s# and c#='006') as 英语, count(*) as 有效课程数, avg(t.score) as 平局成绩 from sc as t group by s# order by avg(t.score)
18、查询各科成绩最高和最低的分: 以如下的形式显示:课程ID,最高分,最低分
select L.c# as 课程ID, L.score as 最高分, R.score as 最低分 from sc L, sc R where L.c# = R.c# and L.score = (select max(IL.score) from sc IL, student as IM where L.c#=IL.c# and IM.s#=IL.s# group by IL.c#) and R.score = (select min(IR.score) from sc as IR where R.c#=IR.c# group by IR.c#);
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.C# AS 课程号, max(course.Cname)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 SC T,Course where t.C#=course.C# GROUP BY t.C# ORDER BY 100 * SUM(CASE WHEN isnull(score,0)>=60 THEN 1 ELSE 0 END)/COUNT(*) DESC
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):
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.T#) AS 教师ID, MAX(Z.Tname) AS 教师姓名, C.C# AS 课程ID, AVG(Score) AS 平均成绩 FROM SC AS T,Course AS C ,Teacher AS Z where T.C#=C.C# and C.T#=Z.T# GROUP BY C.C# ORDER BY AVG(Score) DESC
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):
23、统计下列各科成绩,各分数段人数:课程ID,课程名称,[100-85],[85-70],[70-60],[ 小于60] :
SELECT SC.C# as 课程ID, Cname 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 SC,Course where SC.C#=Course.C# GROUP BY SC.C#,Cname;
24、查询学生平均成绩及其名次:
SELECT 1+(SELECT COUNT( distinct 平均成绩) FROM (SELECT S#,AVG(score) AS 平均成绩 FROM SC GROUP BY S# ) AS T1 WHERE 平均成绩 > T2.平均成绩) as 名次, S# as 学生学号,平均成绩 FROM (SELECT S#,AVG(score) 平均成绩 FROM SC GROUP BY S# ) AS T2 ORDER BY 平均成绩 desc;
25、查询各科成绩前三名的记录(不考虑成绩并列情况):
SELECT t1.S# as 学生ID,t1.C# as 课程ID,Score as 分数 FROM SC t1 WHERE score IN (SELECT TOP 3 score FROM SC WHERE t1.C#= C# ORDER BY score DESC)
26、查询每门课程被选修的学生数:
select c#, count(s#) from sc group by c#;
27、查询出只选修一门课程的全部学生的学号和姓名:
select sc.s#, student.sname, count(c#) as 选课数 from sc,student where sc.s# =student.s# group by sc.s#,Student.sname having count(c#)=1;
28、查询男生、女生人数:
select count(Ssex) as 男生人数 from student group by Ssex having Ssex='男'; select count(Ssex) as 女生人数 from student group by Ssex having Ssex='女';
29、查询姓“张”的学生名单:
select sname from student where sname like '张%';
30、查询同名同姓的学生名单,并统计同名人数:
select sanme,count(*) from student group by sname havang count(*)>1;
31、1981年出生的学生名单(注:student表中sage列的类型是datetime):
select sname, convert(char(11),DATEPART(year,sage)) as age from student where convert(char(11),DATEPART(year,Sage))='1981';
32、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 Sname,SC.S# ,avg(score) from Student,SC where Student.S#=SC.S# group by SC.S#,Sname having avg(score)>85;
33、查询每门课程的平均成绩,结果按平均成绩升序排序,平均成绩相同时,按课程号降序排列:
select C#, avg(score) from sc group by c# order by avg(score), c# desc;
34、查询课程名称为“数据库”,且分数低于60的学生名字和分数:
select sname, isnull(score,0) from student, sc ,course where sc.s#=student.s# and sc.c#=course.c# and course.cname='数据库' and score<60;
35、查询所有学生的选课情况:
select sc.s#,sc.c#,sname,cname from sc,student course where sc.s#=student.s# and sc.c#=course.c#;
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.s#,student.sname,sc.c#,sc.score from student,sc where sc.score>=70 and sc.s#=student.s#;
37、查询不及格的课程,并按课程号从大到小的排列:
select c# from sc where score<60 order by c#;
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 sc.s#,student.sname from sc,student where sc.s#=student.s# and score>80 and c#='003';
39、求选了课程的学生人数:
select count(*) from sc;
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.sname,score from student,sc,course c, teacher where student.s#=sc.S# and sc.c#=c.c# and c.T#=teacher.T# and teacher.tname='叶平' and sc.score=(select max(score) from sc where c#=c.c#);
41、查询各个课程及相应的选修人数:
select count(*) from sc group by c#;
42、查询不同课程成绩相同的学生和学号、课程号、学生成绩:
select distinct a.s#,b.score from sc a ,sc b where a.score=b.score and a.c#<>b.c#;
43、查询每门课程成绩最好的前两名:
select t1.s# as 学生ID,t1.c# 课程ID, Score as 分数 from sc t1 where score in (select top 2 score from sc where t1.c#=c# order by score desc) order by t1.c#;
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序,若人数相同,按课程号升序排序:
select c# as 课程号,count(*) as 人数 from sc group by c# order by count(*) desc c#;
45、检索至少选修两门课程的学生学号:
select s# from sc group by s# having count(*)>=2;
46、查询全部学生选修的课程和课程号和课程名:
select c# ,cname from course where c# in (select c# from sc group by c#);
47、查询没学过”叶平”老师讲授的任一门课程的学生姓名:
select sname from student where s# not in (select s# from course,teacher,sc where course.t#=teacher.t# and sc.c#=course.c# and tname='叶平');
48、查询两门以上不及格课程的同学的学号以及其平均成绩:
select s#,avg(isnull(score,0)) from sc where s# in (select s# from sc where score<60 group by s# having count(*)>2) group by s#;
49、检索“004”课程分数小于60,按分数降序排列的同学学号:
select s# from sc where c#='004' and score<60 order by score desc;
50、删除“002”同学的“001”课程的成绩:
delect from sc where s#='002' and c#='001';