题解 | #每类视频近一个月的转发量/率#

select b.tag,
        sum(a.if_retweet) as retweet_cut,
        round(sum(a.if_retweet)/count(a.start_time),3) as retweet_rate
from tb_user_video_log a
inner 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(a.start_time)) < 30
group by b.tag
order by retweet_rate desc

这题是真垃圾，题不难，理解题是真难