题解 | #每类视频近一个月的转发量/率#

select 
    tag,
    sum(if_retweet) as retweet_cut,
    round(sum(if_retweet)/count(*),3) as retweet_rate
from 
    tb_user_video_log a
    join tb_video_info b on a.video_id = b.video_id
where
    date(start_time) > (
        select date_sub(max(date(start_time)),interval 30 day)
        from tb_user_video_log
    )
group by 
    tag
order by 
    retweet_rate desc