多行日期时间之间的差异

Question

我需要计算客户第一次预订和第二次预订之间的平均时间差。在源表中，客户可以有一个或多个预订。该表显示了 3 个唯一客户以及每个预订的创建时间。

我使用以下查询生成了这张表

select b.customer_id, b.time_created
from booking b
order by b.customer_id

客户预订

customer_id	time_created
32	2021-05-15 10:00:00:000
32	2021-05-24 10:00:00:000
59	2021-05-27 14:00:00:000
71	2021-06-04 15:00:00:000
71	2021-06-05 17:00:00:000
71	2021-06-06 18:00:00:000

期望的输出

customer_id	datetime_diff
32	diff 2021-05-24 10:00:00:000 - 2021-05-15 10:00:00:000)
59	-
71	(2021-06-05 17:00:00:000 - 2021-06-04 15:00:00:000)

更新

customer_id	datetime_diff
1
100	55455498365000
10005	934039000000
10011	120000
10044	634051554000
10053	516000000

Answer 1

您可以使用窗口函数。一种方法：

select customer_id,
       max(time_created) - nullif(min(time_created), max(time_created)) as time_diff
from (select b.*,
             row_number() over (partition by customer_id order by time_created) as seqnum
      from booking b
     ) b
where seqnum <= 2
group by customer_id;

Here 是一个 dbfiddle。