题解 | 播放量峰值top3高的视频

select cid,round(max(peak_uv),3) as max_peak_uv
from(
	select cid,sum(tag)over(partition by cid order by time) as peak_uv
	from(
		select cid,start_time as time,1 as tag
		from play_record_tb
		union all
		select cid,end_time as time,-1 as tag
		from play_record_tb)a)b
group by cid
order by max_peak_uv desc
limit 3