【经典】数据库SQL笔试题目必考详解数据库

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

题目

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:(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) 
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