student_id,course_id,score

select * from s.student_id,s.course_id,s.score from score s left jon (select course_id,max(score) as max_score from score group by score) m on s.course_id=m.course_id and s.score = m.max_score

首先就是子查询查出每一科的最大成绩，然后根据最大成绩和科目连表查处对应的用户。