【mysql经典题目】科目成绩都大于80分\每个科目的第一名\总成绩排名

参考：http://blog.csdn.net/lifushan123/article/details/44948135

1、查询出科目成绩都大于80分的学生的名字？

drop table if EXISTS tmp_1;
create table tmp_1
(`Id` INT NOT NULL AUTO_INCREMENT,
name varchar(10),
subject varchar(10),
score int,
PRIMARY KEY(`Id`));

insert into tmp_1 (name,subject,score) values ('李云龙','语文',79);
insert into tmp_1 (name,subject,score) values ('李云龙','数学',81);
insert into tmp_1 (name,subject,score) values ('楚云飞','语文',81);
insert into tmp_1 (name,subject,score) values ('楚云飞','数学',89);
insert into tmp_1 (name,subject,score) values ('张大彪','语文',79);
insert into tmp_1 (name,subject,score) values ('张大彪','数学',90);

-- 虽然瞟一眼就知道答案是楚云飞，但是我们要通过sql求出结果

select name
from tmp_1
group by name
having sum(score > 80) > 1;

或者

select a.name
from tmp_1 a
left join tmp_1 b on b.name = a.name
where a.score > 80 and b.score > 80 and a.subject != b.subject
group by a.name;

2、查询出每个科目的第一名的学生的学科、姓名、分数[依次是数学、语文]？;

select a.subject,name ,max_score
from tmp_1 a
left join (select subject,max(score) max_score from tmp_1 group by subject) b on  a.score=b.max_score
where a.subject=b.`subject`
order by
case when a.subject='数学' then 1
 when a.subject='语文' then 2 else 3 end ;

3、查询出总成绩排名，字段为姓名和分数，降序展示？;

select name,sum(score)
from tmp_1
group by NAME
order by sum(score) desc;