经典SQL语句面试题

经典SQL语句面试题

以学生表查询来看下常见sql面试题

Student(Sno,Sname,Sage,Ssex) 学生表
Course(Cno,Cname,Tno) 课程表
SC(Sno,Cno,score) 成绩表
Teacher(Tno,Tname) 教师表

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.Sno
from (select Sno,score from SC where Cno=’001′) a,
(select Sno,score from SC where Cno=’002′) b
where a.score>b.score and a.Sno=b.Sno;

2、查询平均成绩大于60分的同学的学号和平均成绩;
select Sno,avg(score)
from sc
group by Sno having avg(score) >60;

3、查询所有同学的学号、姓名、选课数、总成绩;
select Student.Sno,Student.Sname,count(SC.Cno),sum(score)
from Student left Outer join SC on Student.Sno=SC.Sno
group by Student.Sno,Sname

4、查询姓“李”的老师的个数;
select count(distinct(Tname))
from Teacher
where Tname like ‘李%’;

5、查询没学过“叶平”老师课的同学的学号、姓名;
select Student.Sno,Student.Sname
from Student
where Sno not in (select distinct( SC.Sno) from SC,Course,Teacher where SC.Cno=Course.Cno and Teacher.Tno=Course.Tno and Teacher.Tname=’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.Sno,Student.Sname
from Student,SC
where Student.Sno=SC.Sno and SC.Cno=’001′and exists( Select * from SC as SC_2 where SC_2.Sno=SC.Sno and SC_2.Cno=’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 Sno,Sname
from Student
where Sno in
(select Sno
from SC ,Course ,Teacher
where SC.Cno=Course.Cno and Teacher.Tno=Course.Tno and Teacher.Tname=’叶平’ group by Sno having count(SC.Cno)=(select count(Cno) from Course,Teacher where Teacher.Tno=Course.Tno and Tname=’叶平’));

8、查询所有课程成绩小于60分的同学的学号、姓名;
select Sno,Sname
from Student
where Sno not in (select Student.Sno from Student,SC where S.Sno=SC.Sno and score>60);

9、查询没有学全所有课的同学的学号、姓名;
select Student.Sno,Student.Sname
from Student,SC
where Student.Sno=SC.Sno
group by Student.Sno,Student.Sname having count(Cno) <(select count(Cno) from Course);

10、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 Sno,Sname
from Student,SC
where Student.Sno=SC.Sno and Cno in (select Cno from SC where Sno='1001');

11、删除学习“叶平”老师课的SC表记录;
Delect SC
from course ,Teacher
where Course.Cno=SC.Cno and Course.Tno= Teacher.Tno and Tname='叶平';

12、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.Cno 课程ID,L.score 最高分,R.score 最低分
FROM SC L ,SC R
WHERE L.Cno = R.Cno
and
L.score = (SELECT MAX(IL.score)
FROM SC IL,Student IM
WHERE IL.Cno = L.Cno and IM.Sno=IL.Sno
GROUP BY IL.Cno)
and
R.Score = (SELECT MIN(IR.score)
FROM SC IR
WHERE IR.Cno = R.Cno
GROUP BY IR.Cno );

13、查询学生平均成绩及其名次
SELECT 1+(SELECT COUNT( distinct 平均成绩)
FROM (SELECT Sno,AVG(score) 平均成绩
FROM SC
GROUP BY Sno ) T1
WHERE 平均成绩 > T2.平均成绩) 名次, Sno 学生学号,平均成绩
FROM (SELECT Sno,AVG(score) 平均成绩 FROM SC GROUP BY Sno ) T2
ORDER BY 平均成绩 desc;

14、查询各科成绩前三名的记录:(不考虑成绩并列情况)
SELECT t1.Sno as 学生ID,t1.Cno as 课程ID,Score as 分数
FROM SC t1
WHERE score IN (SELECT TOP 3 score
FROM SC
WHERE t1.Cno= Cno
ORDER BY score DESC)
ORDER BY t1.Cno;

15、查询每门功成绩最好的前两名
SELECT t1.Sno as 学生ID,t1.Cno as 课程ID,Score as 分数
FROM SC t1
WHERE score IN (SELECT TOP 2 score
FROM SC
WHERE t1.Cno= Cno
ORDER BY score DESC )
ORDER BY t1.Cno;

补充:
已经知道原表
year salary
——————
2000 1000
2001 2000
2002 3000
2003 4000

解:
select b.year,sum(a.salary)
from salary a,salary b
where a.year<=b.year
group by b.year
order by b.year;

在面试过程中多次碰到一道SQL查询的题目,查询A(ID,Name)表中第31至40条记录,ID作为主键可能是不是连续增长的列,完整的查询语句如下:
方法一:
select top 10 *
from A
where ID >(select max(ID) from (select top 30 ID from A order by ID ) T) order by ID
方法二:
select top 10 *
from A
where ID not In (select top 30 ID from A order by ID)
order by ID