Am 11.12.2017 um 18:09 schrieb Olivier Leprêtre:
>
> Hi,
>
> I have a table describing sort of ordered road segments and their
> associated weight. I would like to calculate weight deltas between two
> consecutive segments. Problem is to substract previous from current
> row and reuses result as input for the next row.
>
You can use the lag() - function.
select ..., lag(weight) over (partition by road order by segment) ...
Regards, Andreas
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