题解 | 输出播放量最高的视频

with t1 as (select cid,start_time as count_time, 1 as count_num from play_record_tb
union all
select cid,end_time as count_time, -1 as count_num from play_record_tb),

t2 as (select cid,count_time,count_num,
sum(count_num)over(partition by cid order by count_time,count_num) as current_num
from t1)

select cid,max(current_num) as max_peak_uv from t2
group by cid
order by max_peak_uv desc
limit 3