[postgis-users] - The greater length River inside one Watershed

[George Silva]

hello marcello. what is your data model? dependng on the data model
(if you have a column, lets say, rivername) you can use a group by
clause and st_collect on your geometry field. ex:

select rivername, max(st_collect(the_geom)) from rivers group by rivername

the intersects clause its up to you , depending on your néds. not
tested, but should work.

On 4/26/11, Marcello Benigno <benigno.marcello at gmail.com> wrote:
> Hi All,
>
> I need a query that returns the greater length of river within a
> watershed. Does
> anyone have any suggestions on how I can solve this problem?
>
> The rivers are formed by segments. if each were a continuous line would be
> easy.
>
> Here is a print-screen of the problem, in yellow is what would be the result
> of
> the query.
>
> Thanks in advance,
> --
> *Marcello Benigno B. de Barros Filho*
> Prof. do Curso Superior de Tecnologia em Geoprocessamento - IFPB
> Mestre em Ciências Geodésicas e Tecnologias da Geoinformação - UFPE
> http://profmarcello.blogspot.com
> http://about.me/marcello.benigno
>


-- 
George R. C. Silva

Desenvolvimento em GIS
http://geoprocessamento.net
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