SQL练习学校场景

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′) as a,
(select s#, score from SC where C#=’002′) as 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#;

SQL练习 学校场景

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