select uid,a1 exam_complete_cnt
from(
select uid,count(start_time) a1,count(submit_time) a2
from(
select uid,exam_id,start_time,submit_time,dense_rank() over(partition by uid order by date_format(start_time, '%Y%m') desc) rankk
from exam_record) t1
where rankk <= 3
group by uid
having a1 = a2) t2
order by exam_complete_cnt desc, uid desc

要点：where的执行在窗口函数之前