题解 | 每类视频近一个月的转发量/率

SELECT
	tag,
	sum(
	IF
	( if_retweet = 1, 1, 0 )) AS retweet_cnt,
	round( sum( IF ( if_retweet = 1, 1, 0 ))/ count(*), 3 ) AS retweet_rate 
FROM
	tb_user_video_log u
	LEFT JOIN tb_video_info v ON u.video_id = v.video_id 
WHERE
	start_time BETWEEN ( SELECT DATE_SUB( max( start_time ), INTERVAL 30 DAY ) AS da FROM tb_user_video_log ) 
	AND start_time 
GROUP BY
	1 
ORDER BY
	3 DESC