题解 | #2021年11月每天的人均浏览文章时长#

select
    date_format (in_time, '%Y-%m-%d'),
    round(sum(timestampdiff (second, in_time, out_time))/count(distinct uid),1) avgtime
from
    tb_user_log
where
    in_time like '2021-11%' and artical_id like '900_'
group by  date_format (in_time, '%Y-%m-%d')
order by avgtime

本题难度不大，因为还要注意客户浏览的未必全部都是文章，需要对于文章这块的内容like'9000_'做限制