select uid, max(days_w) as days_window, round(count(exam_id)/(timestampdiff(day,min(dt),max(dt))+1)*max(days_w),2) as avg_exam_cnt from( select b.uid,exam_id, dt, timestampdiff(day,lag_t,dt)+1 as days_w from( select uid, exam_id, date(start_time) as dt, ...