如何获取同一列中两行之间的差异

Posted 2023-03-25

【中文标题】如何获取同一列中两行之间的差异

【英文标题】：How to get the difference between two rows in the same column

【发布时间】：2020-09-26 01:57:14

【问题描述】：

这就是我到目前为止所拥有的，我正在尝试获取同一列中的行之间的差异。我想不通。我正在尝试在 clickhouse 中查询。

SELECT 
    session_id,
    created,
    DATEDIFF(mi, time1.created, time2.created)
FROM impressions as time1
LEFT JOIN impressions i2 as time2
  ON time1.session_id = time2.session_id + 1

【问题讨论】：

究竟什么“不起作用”？你期待/想要什么，你得到了什么？

【参考方案1】：

查询应该使用dateDiff-function:

SELECT 
    time1.session_id,
    time2.session_id,
    time1.created,
    dateDiff('minute', time2.created, time1.created)
FROM impressions AS time1
LEFT JOIN impressions AS time2 ON time1.session_id = toInt32(time2.session_id + 1)
SETTINGS join_use_nulls = 1

【参考方案2】：

我认为 Clickhouse 中的语法是：

SELECT time1.session_id, time1.created,
       DATEDIFF('minute', time2.created, time1.created)
FROM impressions time1 LEFT JOIN
     impressions i2 time2
     ON time1.session_id = time2.session_id + 1