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#);
SQL数据库面试题以及答案
