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(*),3) as retweet_rate 
from tb_user_video_log a 
left join tb_video_info b 
on a.video_id = b.video_id
where datediff(date((select max(start_time) from tb_user_video_log )),date(start_time)) < 30

group by tag 
order by retweet_rate desc

关键是 最大的日期和日期之前的差值小于30天，就代表视频最近一个月有交互