SELECT date(in_time) dt, round(sum(time_to_sec(timediff(out_time,in_time)))/count(DISTINCT uid),1) AS avg_viiew_len_sec FROM tb_user_log WHERE substr(date(in_time),1,7) = '2021-11' AND artical_id <> 0 GROUP BY dt ORDER BY avg_viiew_len_sec;
SELECT date(in_time) dt, round(sum(time_to_sec(timediff(out_time,in_time)))/count(DISTINCT uid),1) AS avg_viiew_len_sec FROM tb_user_log WHERE substr(date(in_time),1,7) = '2021-11' AND artical_id <> 0 GROUP BY dt ORDER BY avg_viiew_len_sec;