Question

此查询非常适合查找连续行之间的差异：

select id, created_at, created_at - lag(created_at, 1) 
over (order by created_at) as diff
from fistbumps where bumper_id = 2543 
and created_at between '2012-01-11' and '2012-01-12' order by created_at;

......但结果如下：

   id   |         created_at         |      diff       
--------+----------------------------+-----------------
 197230 | 2012-01-11 00:04:31.774426 | 
 197231 | 2012-01-11 00:04:32.279181 | 00:00:00.504755
 197232 | 2012-01-11 00:04:33.961665 | 00:00:01.682484
 197233 | 2012-01-11 00:04:36.506685 | 00:00:02.54502

如果我可以将diff列格式化为秒和毫秒（例如2.54502），那么真正很常见的是。我尝试使用date_trunc（）和extract（），但我似乎无法正确使用语法。

Answer 1

created_at - lag（created_at）的结果是类型interval的值。

您可以使用interval

获取extract(epoch from interval_value)的秒数

所以在你的情况下，它将是：

extract(epoch from (created_at - lag(created_at, 1)) )

PostgreSQL格式滞后列

1 个答案: