mysql关于查询分数的排行
select username,score,(select count(1) from members_exams where score>=(select score from members_exams where ucode='".$vname['ucode']."' order by score desc limit 1)) as rank from members_exams where ucode='".$vname['ucode']."';
select username,score,(select count(1) from members_exams where score>=(select score from members_exams where ucode='".$vname['ucode']."' order by score desc limit 1)) as rank from members_exams where ucode='".$vname['ucode']."';