题解 | 每类视频近一个月的转发量/率

select tag, sum(if_retweet) as retweet_cnt, round(sum(if_retweet) / count(1), 3) as retweet_rate
from tb_user_video_log tuvl
         join tb_video_info t on tuvl.video_id = t.video_id,
     (select max(end_time) as t
      from tb_user_video_log) b
where timestampdiff(day, end_time, b.t) < 30
group by tag
order by retweet_rate desc;