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 AS u
INNER JOIN tb_video_info AS v
        USING(video_id)
    
WHERE 
end_time BETWEEN (SELECT DATE_SUB(MAX(end_time), INTERVAL 30 DAY) FROM tb_user_video_log) AND (SELECT MAX(end_time) FROM tb_user_video_log) 

GROUP BY tag

ORDER BY retweet_rate DESC