1、查询"01"课程比"02"课程成绩高的学生的信息及课程分数
select *
from score sc1,score sc2
where sc1.c_id='01' and sc2.c_id='02'
and sc1.s_id = sc2.s_id and sc1.score > sc2.score;
2、查询"01"课程比"02"课程成绩低的学生的信息及课程分数
select *
from score sc1,score sc2
where sc1.c_id='01' and sc2.c_id='02'
and sc1.s_id = sc2.s_id and sc1.score < sc2.score;
3、查询平均成绩大于等于60分的同学的学生编号和学生姓名和平均成绩
select s.s_id,stu.s_sname,avg(s.score) from score s
inner join student stu on stu.s_id = s.s_id
group by s.s_id having avg(s.score) >=60
4、查询平均成绩小于60分的同学的学生编号和学生姓名和平均成绩
select student.sid,student.sname,avg(sc.score)
from student,sc
where student.sid = sc.scid group by student.sid
having avg(sc.score)<60
5、查询所有同学的学生编号、学生姓名、选课总数、所有课程的总成绩
select s.s_id '编号',s.s_sname '学生姓名',ss.countcou ' 选课总数',
ss.sumscore '总成绩' from student s,
(select sc.s_id, sum(sc.score) as sumscore,count(sc.c_id) as countcou from score sc group by sc.s_id) as ss where s.s_id = ss.s_id
6、查询"李"姓老师的数量
select count(*) from teacher t where t.t_name like '李%';
7、查询学过"张三"老师授课的同学的信息
select * from student stu
where stu.s_id in(
select sc.s_id from score sc
where sc.c_id in(
select c.c_id from course c
where c.t_id = (
select t.t_id from teacher t
where t.t_name = '张三'
)
)
)
8、查询没学过"张三"老师授课的同学的信息
select * from student stu
where stu.s_id not in(
select sc.s_id from score sc
where sc.c_id in(
select c.c_id from course c
where c.t_id = (
select t.t_id from teacher t
where t.t_name = '张三'
)
)
)
9、查询学过编号为"01"并且也学过编号为"02"的课程的同学的信息
select * from student
where s_id in (select sc1.s_id from score sc1,score sc2
where sc1.s_id = sc2.s_id and sc1.c_id = '01' and sc2.c_id = '02');
10、查询学过编号为"01"但是没有学过编号为"02"的课程的同学的信息
select s.*, sc1.score,sc2.score from student s
left join (select * from score where c_id = '01') sc1 on s.s_id = sc1.s_id
left join (select * from score where c_id = '02') sc2 on s.s_id = sc2.s_id
where sc1.c_id = '01' and sc2.c_id is null;
11、查询没有学全所有课程的同学的信息
select * from student stu
where stu.s_id in(
select sc.s_id from score sc
group by sc.s_id
having count(sc.c_id) < (select count(*) from course))
12、查询至少有一门课与学号为"01"的同学所学相同的同学的信息
select * from student stu
where stu.s_id in(
select sc1.s_id from score sc1
where sc1.course in(
select sc2.c_id from score sc2
where sc2.s_id ='01'))
and stu.s_id !='01';
13、查询和"01"号的同学学习的课程完全相同的其他同学的信息
select * from student where s_id in
(select s_id from score where s_id not in
(select s_id from score where c_id not in
(select c_id from score where s_id = '01'
)
) group by s_id
having count(c_id) =
(select count(c_id) from score where s_id = '01')
and s_id != '01'
)
14、查询没学过"张三"老师讲授的任一门课程的学生姓名
select stu.s_name from student stu where stu.s_id not in
(select score.s_id from score where score.c_id in
(select course.c_id from course,teacher where course.t_id and t_name='张三'))；
15、查询两门及其以上不及格课程的同学的学号，姓名及其平均成绩
select
student.s_id,
student.s_name,
avg(score.score)
from student,score
where student.s_id = score.s_id
and score.score < 60 group by score.s_id
having count(*) > 1;
16、检索"01"课程分数小于60，按分数降序排列的学生信息
select s.*,b.score from student a
inner join score b
where b.c_id='01'and b.score < 60
order by score desc;
17、按平均成绩从高到低显示所有学生的所有课程的成绩以及平均成绩
第一种：
select a.*,b.sc01,c.sc02,d.sc03,avg(dd.score) as avgN
from student a
left join (
select s_id,score as 'sc01' from score where c_id='01'
) b on a.s_id=b.s_id
left join (
select s_id,score as 'sc02' from score where c_id='02'
) c on a.s_id=c.s_id
left join (
select s_id,score as 'sc03' from score where c_id='03'
) d on a.s_id=d.s_id
left join score dd on a.s_id=dd.s_id
group by s_id
order by avg(dd.score) desc
第二种：
SELECT a.*
,SUM(CASE WHEN b.c_id='01' THEN b.score ELSE 0 END) AS s01
,SUM(CASE WHEN b.c_id='02' THEN b.score ELSE 0 END) AS s02
,SUM(CASE WHEN b.c_id='03' THEN b.score ELSE 0 END) AS s03
,AVG(CASE WHEN b.score IS NULL THEN 0 ELSE b.score END) avs
FROM student a
LEFT JOIN score b
ON a.s_id=b.s_id
GROUP BY a.s_id,a.s_name,a.s_age,a.s_sex
ORDER BY avs DESC;
18、查询每门课程被选修的学生数
select
sc.c_id,count(*)
from score sc
group by sc.c_id;
19、查询出只有两门课程的全部学生的学号和姓名
select stu.s_id,stu.s_name,count(sc.c_id) '选修课程俩门' from
student as stu
inner join
score as sc on stu.s_id = sc.s_id
group by stu.s_id having count(sc.c_id)=2;
20、查询男生、女生人数
select nv.a '男'，nan.b '女' from
（select count(*) as a from student where s_sex like '女'） nv,
(select count(*) as b from student where s_sex like '男'） nan
21、查询名字中含有"风"字的学生信息
select * from student where s_name like '%风%';
22、查询同名同姓学生名单，并统计同名人数
select s_name,count(*） from student
group by s_name having count(s_name) > 1
23、查询1990年出生的学生名单
select * from student where s_age like '1990%';
24、查询每门课程的平均成绩，结果按平均成绩降序排列，平均成绩相同时，按课程编号
selec c_id,avg(score) from
score grouo by c_id order by avg(score) desc,c_id desc;
25、查询平均成绩大于等于85的所有学生的学号、姓名和平均成绩
select * from student stu inner join score sc on stu.s_id = sc.s_id
group by stu.s_id having
avg(sc.score)>=85
26、查询课程名称为"数学"，且分数低于60的学生姓名和分数
select b.sname,a.score from (select * from sc where score<60
and cid =(select cid from course where cname='数学')) A
left join student B
on A.scid = b.sid;
27、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 st.s_name as 姓名,co.c_name as 课程名，sc.score as 分数
from score sc,course co,student st
where sc.score > 70 and
sc.s_id = st.s_id and
sc.c_id = co.c_id;
27-1，查询所有课程成绩在70分以上的姓名、课程名称和分数
SELECT a.s_id,c.s_name,a.score FROM
(SELECT s_id,score,COUNT(c_id)as NN FROM score
WHERE score > 70 GROUP BY s_id)as a
INNER JOIN
(SELECT s_id,COUNT(c_id)as NN FROM score
GROUP BY s_id)as b
ON a.s_id=b.s_id
INNER join
student as c
ON a.s_id=c.s_id
select s.s_name '姓名',c_name '课程',a.score '分数'
from student s,
(select s_id,score,count(c_id)as nn from score
where score > 70 group by s_id)as a,
(select s_id,count(c_id)as nn from score group by s_id)as b,
course d
where a.nn = b.nn and a.s_id = b.s_id and s.s_id = b.s_id
group by s.s_name,a.score,c_name
28、查询不及格的课程
select c_id from score where score < 60 group by c_id
29、查询课程编号为01且课程成绩在80分以上的学生的学号和姓名
select stu.s_id '学号',stu.s_sname '姓名' from score sc
inner join student stu on sc.s_id = stu.s_id = 01 and
sc.score > 80;
30、求每门课程的学生人数
select c.c_name as 课程名,count(*) as 课程人数
from course c inner join score s on c.c_id = s.c_id
group by c.c_id,c.c_name
31、查询不同课程成绩相同的学生的学生编号、课程编号、学生成绩
select distinct A.s_id,B.score from score A ,score B where A.score=B.score and A.c_id <>B.c_id ;
32、查询每门功成绩最好的前两名
select sc.s_id as 学生ID,sc.c_id as 课程ID,score as 分数
from score sc
where score in (select top2 score
from score
where sc.c_id= c_id
order by score desc
)
order by sc.c_id;
33、检索至少选修两门课程的学生学号
select s_id
from score
group by s_id
having count(*) >= 2
34、查询选修了全部课程的学生信息
select *
from course
where c_id in (select c_id from score group by c_id)