题解 | 每类视频近一个月的转发量/率

select 
    tag,sum(if_retweet) as reweet_cnt,
    round(avg(if_retweet),3) as retweet_rate
from
(
select * from tb_user_video_log e1

where timestampdiff(DAY,end_time,
    (select max(end_time) from tb_user_video_log ))<30
	##############这里的SQL不要写成 select max(end_time) from tb_user_video_log where video_id=e1.video_id
) lastest_month_t

inner join tb_video_info e2
on lastest_month_t.video_id = e2.video_id
group by tag
order by retweet_rate desc