select uid,round(avg(score),0) avg_score,round(avg(time_took),1) abg_time_took from ( select a.uid,ifnull(score,0) score ,if(submit_time is null,duration,timestampdiff(minute,start_time,submit_time)) time_took from exam_record a,examination_info b,user_info c where a.uid = c.uid and b.exam_id = a.ex...