一、数据表 student(s#,sname,sage,ssex) 学生表 s#：学号；sname：学生姓名；sage：学生年龄；ssex：学生性别 course(c#,cname,t#) 课程表 c#,课程编号；cname：课程名字；t#：教师编号 sc(s#,c#,score) 成绩表 s#：学号；c#,课程编号；score：成绩 teacher(
一、数据表 student(s#,sname,sage,ssex) 学生表 s#：学号；sname：学生姓名；sage：学生年龄；ssex：学生性别
course(c#,cname,t#) 课程表 c#,课程编号；cname：课程名字；t#：教师编号
sc(s#,c#,score) 成绩表 s#：学号；c#,课程编号；score：成绩
teacher(t#,tname) 教师表 t#：教师编号； tname：教师名字二、基本操作：
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 s#,sname from (select student.s#,student.sname,score ,(select score from sc sc_2 where sc_2.s#=student.s# and sc_2.c#='002') score2 from student,sc where student.s#=sc.s# and c#='001') s_2 where score2 60);
10、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#) =60 then 1 else 0 end)/count(*) as 及格百分数 from sc t,course where t.c#=course.c# group by t.c# order by 100 * sum(case when isnull(score,0)>=60 then 1 else 0 end)/count(*) desc
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 c# ='001' then score else 0 end)/sum(case c# when '001' then 1 else 0 end) as 企业管理平均分 ,100 * sum(case when c# = '001' and score >= 60 then 1 else 0 end)/sum(case when c# = '001' then 1 else 0 end) as 企业管理及格百分数 ,sum(case when c# = '002' then score else 0 end)/sum(case c# when '002' then 1 else 0 end) as 马克思平均分 ,100 * sum(case when c# = '002' and score >= 60 then 1 else 0 end)/sum(case when c# = '002' then 1 else 0 end) as 马克思及格百分数 ,sum(case when c# = '003' then score else 0 end)/sum(case c# when '003' then 1 else 0 end) as uml平均分 ,100 * sum(case when c# = '003' and score >= 60 then 1 else 0 end)/sum(case when c# = '003' then 1 else 0 end) as uml及格百分数 ,sum(case when c# = '004' then score else 0 end)/sum(case c# when '004' then 1 else 0 end) as 数据库平均分 ,100 * sum(case when c# = '004' and score >= 60 then 1 else 0 end)/sum(case when c# = '004' then 1 else 0 end) as 数据库及格百分数 from sc
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.t#) as 教师id,max(z.tname) as 教师姓名,c.c# as 课程ｉｄ,max(c.cname) as 课程名称,avg(score) as 平均成绩 from sc as t,course as c ,teacher as z where t.c#=c.c# and c.t#=z.t# group by c.c# order by avg(score) desc
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 sc.s# as 学生学号, student.sname 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,sc left join sc as t1 on sc.s# = t1.s# and t1.c# = '001' left join sc as t2 on sc.s# = t2.s# and t2.c# = '002' left join sc as t3 on sc.s# = t3.s# and t3.c# = '003' left join sc as t4 on sc.s# = t4.s# and t4.c# = '004' where student.s#=sc.s# 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 sc left join sc as t1 on sc.s# = t1.s# and t1.c# = 'k1' left join sc as t2 on sc.s# = t2.s# and t2.c# = 'k2' left join sc as t3 on sc.s# = t3.s# and t3.c# = 'k3' left join sc as t4 on sc.s# = t4.s# and t4.c# = 'k4' order by isnull(t1.score,0) + isnull(t2.score,0) + isnull(t3.score,0) + isnull(t4.score,0) desc);
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],[ 1;;
31、1981年出生的学生名单(注：student表中sage列的类型是datetime) select sname, convert(char (11),datepart(year,sage)) as age from student where convert(char(11),datepart(year,sage))='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 c#,avg(score) from sc group by c# order by avg(score),c# desc ;
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 sname,sc.s# ,avg(score) from student,sc where student.s#=sc.s# group by sc.s#,sname 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 sname,isnull(score,0) from student,sc,course where sc.s#=student.s# and sc.c#=course.c# and course.cname='数据库'and score =70 and sc.s#=student.s#;
37、查询不及格的课程，并按课程号从大到小排列 select c# from sc where scor e 80 and c#='003';
39、求选了课程的学生人数 select count(*) from sc;
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.sname,score from student,sc,course c,teacher where student.s#=sc.s# and sc.c#=c.c# and c.t#=teacher.t# and teacher.tname='叶平' and sc.score=(select max(score)from sc where c#=c.c# );
41、查询各个课程及相应的选修人数 select count(*) from sc group by c#;
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.s#,b.score from sc a ,sc b where a.score=b.score and a.c# b.c# ;
43、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#;
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 c# as 课程号,count(*) as 人数 from sc group by c# order by count(*) desc,c#
45、检索至少选修两门课程的学生学号 select s# from sc group by s# 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 c#,cname from course where c# in (select c# from sc group by c#)
47、查询没学过“叶平”老师讲授的任一门课程的学生姓名 select sname from student where s# not in (select s# from course,teacher,sc where course.t#=teacher.t# and sc.c#=course.c# and tname='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 s#,avg(isnull(score,0)) from sc where s# in (select s# from sc where score 2)group by s#;
49、检索“004”课程分数小于60，按分数降序排列的同学学号
select s# from sc where c#='004'and score <60 order by score desc;
50、删除“002”同学的“001”课程的成绩 delete from sc where s#='002'and c#='001';