select DATE_FORMAT(in_time, "%Y-%m-%d") td, round( sum(TIMESTAMPDIFF(second, in_time, out_time)) / count(distinct uid), 1 ) avg_viiew_len_sec from tb_user_log where YEAR(in_time) = '2021' and MONTH(in_time) = '11' and artical_id <> '0' group by DATE_FORMAT(in_time, "%Y-%m-%d") order by avg_viiew_len_sec