student(stuid,stuname,stuage,stusex) 学生表
stuid：学号；stuname：学生姓名；stuage：学生年龄；stusex：学生性别
course(courseid,coursename,teacherid) 课程表
courseid,课程编号；coursename：课程名字；teacherid：教师编号
scores(stuid,courseid,score) 成绩表
stuid：学号；courseid,课程编号；score：成绩
teacher(teacherid,teachername) 教师表
teacherid：教师编号； teachername：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.stuid from (select stuid,score from scores where courseid='001') a,(select stuid,score
from scores where courseid='002') b
where a.score>b.score and a.stuid=b.stuid;
2、查询平均成绩大于60分的同学的学号和平均成绩；
select stuid,avg(score)
from scores
group by stuid having avg(score) >60;
3、查询所有同学的学号、姓名、选课数、总成绩；
select student.stuid,student.stuname,count(scores.courseid),sum(score)
from student left outer join scores on student.stuid=scores.stuid
group by student.stuid,stuname
4、查询姓“李”的老师的个数；
select count(distinct(teachername))
from teacher
where teachername like '李%';
5、查询没学过“叶平”老师课的同学的学号、姓名；
select student.stuid,student.stuname
from student
where stuid not in (select distinct( scores.stuid) from scores,course,teacher where scores.courseid=course.courseid and teacher.teacherid=course.teacherid and teacher.teachername='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.stuid,student.stuname from student,scores where student.stuid=scores.stuid and scores.courseid='001'and exists( select * from scores as scores_2 where scores_2.stuid=scores.stuid and scores_2.courseid='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 stuid,stuname
from student
where stuid in (select stuid from scores ,course ,teacher where scores.courseid=course.courseid and teacher.teacherid=course.teacherid and teacher.teachername='叶平' group by stuid having count(scores.courseid)=(select count(courseid) from course,teacher where teacher.teacherid=course.teacherid and teachername='叶平'));
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 stuid,stuname from (select student.stuid,student.stuname,score ,(select score from scores scores_2 where scores_2.stuid=student.stuid and scores_2.courseid='002') score2
from student,scores where student.stuid=scores.stuid and courseid='001') s_2 where score2 9、查询所有课程成绩小于60分的同学的学号、姓名；
select stuid,stuname
from student
where stuid not in (select student.stuid from student,scores where s.stuid=scores.stuid and score>60);
10、查询没有学全所有课的同学的学号、姓名；
select student.stuid,student.stuname
from student,scores
where student.stuid=scores.stuid group by student.stuid,student.stuname having count(courseid)
11、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 stuid,stuname from student,scores where student.stuid=scores.stuid and courseid in select courseid from scores where stuid='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 scores.stuid,stuname
from student,scores
where student.stuid=scores.stuid and courseid in (select courseid from scores where stuid='001');
13、把“scores”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 scores set score=(select avg(scores_2.score)
from scores scores_2
where scores_2.courseid=scores.courseid ) from course,teacher where course.courseid=scores.courseid and course.teacherid=teacher.teacherid and teacher.teachername='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 stuid from scores where courseid in (select courseid from scores where stuid='1002')
group by stuid having count(*)=(select count(*) from scores where stuid='1002');
15、删除学习“叶平”老师课的scores表记录；
delect scores
from course ,teacher
where course.courseid=scores.courseid and course.teacherid= teacher.teacherid and teachername='叶平';
16、向scores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、2、
号课的平均成绩；
insert scores select stuid,'002',(select avg(score)
from scores where courseid='002') from student where stuid not in (select stuid from scores where courseid='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 stuid as 学生id
,(select score from scores where scores.stuid=t.stuid and courseid='004') as 数据库
,(select score from scores where scores.stuid=t.stuid and courseid='001') as 企业管理
,(select score from scores where scores.stuid=t.stuid and courseid='006') as 英语
,count(*) as 有效课程数, avg(t.score) as 平均成绩
from scores as t
group by stuid
order by avg(t.score)
18、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.courseid as 课程id,l.score as 最高分,r.score as 最低分
from scores l ,scores as r
where l.courseid = r.courseid and
l.score = (select max(il.score)
from scores as il,student as im
where l.courseid = il.courseid and im.stuid=il.stuid
group by il.courseid)
and
r.score = (select min(ir.score)
from scores as ir
where r.courseid = ir.courseid
group by ir.courseid
);
19、按各科平均成绩从低到高和及格率的百分数从高到低顺序
select t.courseid as 课程号,max(course.coursename)as 课程名,isnull(avg(score),0) as 平均成绩
,100 * sum(case when isnull(score,0)>=60 then 1 else 0 end)/count(*) as 及格百分数
from scores t,course
where t.courseid=course.courseid
group by t.courseid
order by 100 * sum(case when isnull(score,0)>=60 then 1 else 0 end)/count(*) descores
20、查询如下课程平均成绩和及格率的百分数(用1行显示): 企业管理（001），马克思（002），oo¨ （003），数据库（004）
select sum(case when courseid ='001' then score else 0 end)/sum(case courseid when '001' then 1 else 0 end) as 企业管理平均分
,100 * sum(case when courseid = '001' and score >= 60 then 1 else 0 end)/sum(case when courseid = '001' then 1 else 0 end) as 企业管理及格百分数
,sum(case when courseid = '002' then score else 0 end)/sum(case courseid when '002' then 1 else 0 end) as 马克思平均分
,100 * sum(case when courseid = '002' and score >= 60 then 1 else 0 end)/sum(case when courseid = '002' then 1 else 0 end) as 马克思及格百分数
,sum(case when courseid = '003' then score else 0 end)/sum(case courseid when '003' then 1 else 0 end) as uml平均分
,100 * sum(case when courseid = '003' and score >= 60 then 1 else 0 end)/sum(case when courseid = '003' then 1 else 0 end) as uml及格百分数
,sum(case when courseid = '004' then score else 0 end)/sum(case courseid when '004' then 1 else 0 end) as 数据库平均分
,100 * sum(case when courseid = '004' and score >= 60 then 1 else 0 end)/sum(case when courseid = '004' then 1 else 0 end) as 数据库及格百分数
from scores
21、查询不同老师所教不同课程平均分从高到低显示
select max(z.teacherid) as 教师id,max(z.teachername) as 教师姓名,c.courseid as 课程ｉｄ,max(c.coursename) as 课程名称,avg(score) as 平均成绩
from scores as t,course as c ,teacher as z
where t.courseid=c.courseid and c.teacherid=z.teacherid
group by c.courseid
order by avg(score) descores
22、查询如下课程成绩第 3 名到第 6 名的学生成绩单：企业管理（001），马克思（002），uml （003），数据库（004）
[学生id],[学生姓名],企业管理,马克思,uml,数据库,平均成绩
select distinct top 3
scores.stuid as 学生学号,
student.stuname as 学生姓名 ,
t1.score as 企业管理,
t2.score as 马克思,
t3.score as uml,
t4.score as 数据库,
isnull(t1.score,0) + isnull(t2.score,0) + isnull(t3.score,0) + isnull(t4.score,0) as 总分
from student,scores left join scores as t1
on scores.stuid = t1.stuid and t1.courseid = '001'
left join scores as t2
on scores.stuid = t2.stuid and t2.courseid = '002'
left join scores as t3
on scores.stuid = t3.stuid and t3.courseid = '003'
left join scores as t4
on scores.stuid = t4.stuid and t4.courseid = '004'
where student.stuid=scores.stuid and
isnull(t1.score,0) + isnull(t2.score,0) + isnull(t3.score,0) + isnull(t4.score,0)
not in
(select
distinct
top 15 with ties
isnull(t1.score,0) + isnull(t2.score,0) + isnull(t3.score,0) + isnull(t4.score,0)
from scores
left join scores as t1
on scores.stuid = t1.stuid and t1.courseid = 'k1'
left join scores as t2
on scores.stuid = t2.stuid and t2.courseid = 'k2'
left join scores as t3
on scores.stuid = t3.stuid and t3.courseid = 'k3'
left join scores as t4
on scores.stuid = t4.stuid and t4.courseid = 'k4'
order by isnull(t1.score,0) + isnull(t2.score,0) + isnull(t3.score,0) + isnull(t4.score,0) descores);
23、统计列印各科成绩,各分数段人数:课程id,课程名称,[100-85],[85-70],[70-60],[
select scores.courseid as 课程id, coursename as 课程名称
,sum(case when score between 85 and 100 then 1 else 0 end) as [100 - 85]
,sum(case when score between 70 and 85 then 1 else 0 end) as [85 - 70]
,sum(case when score between 60 and 70 then 1 else 0 end) as [70 - 60]
,sum(case when score
from scores,course
where scores.courseid=course.courseid
group by scores.courseid,coursename;
24、查询学生平均成绩及其名次
select 1+(select count( distinct 平均成绩)
from (select stuid,avg(score) as 平均成绩
from scores
group by stuid
) as t1
where 平均成绩 > t2.平均成绩) as 名次,
stuid as 学生学号,平均成绩
from (select stuid,avg(score) 平均成绩
from scores
group by stuid
) as t2
order by 平均成绩 descores;
25、查询各科成绩前三名的记录:(不考虑成绩并列情况)
select t1.stuid as 学生id,t1.courseid as 课程id,score as 分数
from scores t1
where score in (select top 3 score
from scores
where t1.courseid= courseid
order by score descores
)
order by t1.courseid;
26、查询每门课程被选修的学生数
select courseid,count(stuid) from scores group by courseid;
27、查询出只选修了一门课程的全部学生的学号和姓名
select scores.stuid,student.stuname,count(courseid) as 选课数
from scores ,student
where scores.stuid=student.stuid group by scores.stuid ,student.stuname having count(courseid)=1;
28、查询男生、女生人数
select count(stusex) as 男生人数 from student group by stusex having stusex='男';
select count(stusex) as 女生人数 from student group by stusex having stusex='女'；
29、查询姓“张”的学生名单
select stuname from student where stuname like '张%';
30、查询同名同性学生名单，并统计同名人数
select stuname,count(*) from student group by stuname having count(*)>1;;
31、1981年出生的学生名单(注：student表中stuage列的类型是datetime)
select stuname, convert(char (11),datepart(year,stuage)) as age
from student
where convert(char(11),datepart(year,stuage))='1981';
32、查询每门课程的平均成绩，结果按平均成绩升序排列，平均成绩相同时，按课程号降序排列
select courseid,avg(score) from scores group by courseid order by avg(score),courseid descores ;
33、查询平均成绩大于85的所有学生的学号、姓名和平均成绩
select stuname,scores.stuid ,avg(score)
from student,scores
where student.stuid=scores.stuid group by scores.stuid,stuname having avg(score)>85;
34、查询课程名称为“数据库”，且分数低于60的学生姓名和分数
select stuname,isnull(score,0)
from student,scores,course
where scores.stuid=student.stuid and scores.courseid=course.courseid and course.coursename='数据库'and score
35、查询所有学生的选课情况；
select scores.stuid,scores.courseid,stuname,coursename
from scores,student,course
where scores.stuid=student.stuid and scores.courseid=course.courseid ;
36、查询任何一门课程成绩在70分以上的姓名、课程名称和分数；
select distinct student.stuid,student.stuname,scores.courseid,scores.score
from student,scores
where scores.score>=70 and scores.stuid=student.stuid;
37、查询不及格的课程，并按课程号从大到小排列
select courseid from scores where scoresor e
38、查询课程编号为003且课程成绩在80分以上的学生的学号和姓名；
select scores.stuid,student.stuname from scores,student where scores.stuid=student.stuid and score>80 and courseid='003';
39、求选了课程的学生人数
select count(*) from scores;
40、查询选修“叶平”老师所授课程的学生中，成绩最高的学生姓名及其成绩
select student.stuname,score
from student,scores,course c,teacher
where student.stuid=scores.stuid and scores.courseid=c.courseid and c.teacherid=teacher.teacherid and teacher.teachername='叶平' and scores.score=(select max(score)from scores where courseid=c.courseid );
41、查询各个课程及相应的选修人数
select count(*) from scores group by courseid;
42、查询不同课程成绩相同的学生的学号、课程号、学生成绩
select distinct a.stuid,b.score from scores a ,scores b where a.score=b.score and a.courseid b.courseid ;
43、查询每门功成绩最好的前两名
select t1.stuid as 学生id,t1.courseid as 课程id,score as 分数
from scores t1
where score in (select top 2 score
from scores
where t1.courseid= courseid
order by score descores
)
order by t1.courseid;
44、统计每门课程的学生选修人数（超过10人的课程才统计）。要求输出课程号和选修人数，查询结果按人数降序排列，查询结果按人数降序排列，若人数相同，按课程号升序排列
select courseid as 课程号,count(*) as 人数
from scores
group by courseid
order by count(*) descores,courseid
45、检索至少选修两门课程的学生学号
select stuid
from scores
group by stuid
having count(*) > = 2
46、查询全部学生都选修的课程的课程号和课程名
select courseid,coursename
from course
where courseid in (select courseid from scores group by courseid)
47、查询没学过“叶平”老师讲授的任一门课程的学生姓名
select stuname from student where stuid not in (select stuid from course,teacher,scores where course.teacherid=teacher.teacherid and scores.courseid=course.courseid and teachername='叶平');
48、查询两门以上不及格课程的同学的学号及其平均成绩
select stuid,avg(isnull(score,0)) from scores where stuid in (select stuid from scores where score 2)group by stuid;
49、检索“004”课程分数小于60，按分数降序排列的同学学号
select stuid from scores where courseid='004'and score
50、删除“002”同学的“001”课程的成绩
delete from scores where stuid='002'and courseid='001';