Re: Windowing ?

Andreas Kretschmer <[email protected]> Mon, 11 Dec 2017 18:15:56 +0100

Newsgroups	gmane.comp.db.postgresql.sql
Message-ID	<[email protected]>


Am 11.12.2017 um 18:09 schrieb Olivier LeprÃªtre:
>
> 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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