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Re: use off geometric types

From: "(dot)"(at)babolo(dot)ru
To: dhoubrechts <dhoubrechts(at)cybernet(dot)be>
Cc: "pgsql-interfaces(at)postgresql(dot)org" <pgsql-interfaces(at)postgresql(dot)org>
Subject: Re: use off geometric types
Date: 2003-02-27 23:32:03
Message-ID: (view raw, whole thread or download thread mbox)
Lists: pgsql-interfaces
> I create a db : createdb geo
> I log into the db :  psql geo
> I create a table named poly :
> geo=# create table poly (parc varchar(15), graphic polygon);
> I populate the table : 
> insert into poly values('A52','(2,1),(1,3),(2,5),(4,6),(6,4),(5,2)');
> insert into poly values('A135','(3,3),(7,4),(8,2),(4,1)');
> Now I would look if the first polygon overlaps the second using the
> varchars for retriving the poly.
> I could do it so :
> geo=# select '((2,1),(1,3),(2,5),(4,6),(6,4),(5,2))'::polygon &&
> '((3,3),(7,4),(8,2),(4,1))'::polygon;
>  ?column?
> ----------
>  t
> (1 row)
> Now, how can I do to have something like :
> geo=# select graphic::polygon  from poly where parc='A52' && select
> graphic::polygon from poly where parc='A135';
SELECT a.graphic && b.graphic FROM poly a, poly b WHERE a.parc='A52' AND b.parc='A135';

But if you want to find all overlaps
SELECT a.parc, b.parc FROM poly a, poly b WHERE a.graphic && b.graphic;

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