题解 | #2021年11月每天的人均浏览文章时长#
2021年11月每天的人均浏览文章时长
https://www.nowcoder.com/practice/8e33da493a704d3da15432e4a0b61bb3
SELECT
dt,
ROUND(SUM(duration) / COUNT(DISTINCT uid), 1) avg_viiew_len_sec
FROM
(
SELECT
uid,
artical_id,
SUBSTRING(in_time, 1, 10) dt,
TIMESTAMPDIFF (SECOND, in_time, out_time) duration
FROM
tb_user_log
WHERE
SUBSTRING(in_time, 1, 10) BETWEEN '2021-11-01' AND '2021-11-30'
AND artical_id != 0
) t1
GROUP BY
dt
ORDER BY
avg_viiew_len_sec;
采用子查询的方法提取中间表格，这样处理起来比较方便。
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