select uid,level,register_time ,max(score) maxscore from user_info join exam_record using(uid) where uid in (select distinct exam_record.uid from user_info left join exam_record using(uid) join examination_info using(exam_id) where job = '算法' and tag = '算法' and date_format(register_time,'%Y%m%d') = date_format(submit_time,'%Y%m%d')) group by uid order by maxscore desc limit 6,3