sql面试

1.用一条SQL语句 查询出每门课都大于80分的学生姓名

name   kecheng   fenshu
张三     语文       81
张三     数学       75
李四     语文       76
李四     数学       90
王五     语文       81
王五     数学       100
王五     英语       90

A: select distinct name from table  where  name not in (select distinct name from table where fenshu<=80)

2.一道SQL语句面试题，关于group by
表内容：
2005-05-09 胜
2005-05-09 胜
2005-05-09 负
2005-05-09 负
2005-05-10 胜
2005-05-10 负
2005-05-10 负

如果要生成下列结果, 该如何写sql语句?

胜 负
2005-05-09 2 2
2005-05-10 1 2
------------------------------------------
使用函数连接：
SELECT rq,SUM(CASE  WHEN shengfu='胜' THEN 1 ELSE 0 END) 胜,SUM(CASE WHEN shengfu='负' THEN 1 ELSE 0 END) 负 FROM tmp GROUP BY rq;
外连接：
SELECT n.rq,n.胜,m.负 FROM (SELECT rq,COUNT(*) 胜 FROM tmp WHERE shengfu='胜' GROUP BY rq) n INNER JOIN (SELECT rq,COUNT(*) 负 FROM tmp WHERE shengfu='负' GROUP BY rq) m ON n.rq=m.rq;
自连接：
SELECT a.rq, a.a1 胜,b.b1 负 FROM
(SELECT rq,COUNT(rq) a1 FROM tmp WHERE shengfu='胜' GROUP BY rq)a,
(SELECT rq,COUNT(rq) b1 FROM tmp WHERE shengfu='负' GROUP BY rq)b
 WHERE a.rq=b.rq;

一个表中的Id有多个记录，把所有这个id的记录查出来，并显示共有多少条记录数。
------------------------------------------
select id, Count（*) from tb group by id having count(*)>1
select * from(select count(ID) as count from table group by ID)T where T.count>1

SQL资料：和我们在课堂上所学的较大的不同在于：子查询的位置非常灵活，可以出现在from子句后（需要为此查询取别名），
也可以出现在select的目标列中，请仔细读懂下列例子（有的地方取别名直接就空格后出现别名，有的地方是用as后面跟别名的方式）。
注：主要是学习基本语句或短语的用法

Student(S#,Sname,Sage,Ssex) 学生表
Course(C#,Cname,T#) 课程表
SC(S#,C#,score) 成绩表
Teacher(T#,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.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、查询没学过“叶平”老师课的同学的学号、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 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.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′);
7、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’));

8、查询所有课程成绩小于60分的同学的学号、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);

9、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);

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 S#,Sname
from Student,SC
where Student.S#=SC.S# and C# in （select C# from SC where S#='1001'）;

11、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';

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

13、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) 平均成绩
FROM SC
GROUP BY S# ) T1
WHERE 平均成绩 > T2.平均成绩) 名次, S# 学生学号,平均成绩
FROM (SELECT S#,AVG(score) 平均成绩 FROM SC GROUP BY S# ) T2
ORDER BY 平均成绩 desc;

14、查询各科成绩前三名的记录:(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
(select distinct score from SC order) by score desc)
ORDER BY t1.C#;

(2)、查询各科成绩前三名的记录:(bu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)
ORDER BY t1.C#;

15、查询每门功成绩最好的前两名
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 2 score
FROM SC
WHERE t1.C#= C#
ORDER BY score DESC )
ORDER BY t1.C#;

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

.学生表 如下:
自动编号   学号   姓名课程编号课程名称分数
1        2005001
张三 0001      数学    69
2        2005002 李四 0001      数学    89
3        2005001 张三 0001      数学    69
删除除了自动编号不同,其他都相同的学生冗余信息

A: delete tablename where
自动编号 not in(select min(自动编号) from tablename group by 学号,姓名,课程编号,课程名称,分数)