Date: Sat, 1 Mar 2003 10:37:30 +0200
From: "Victor Yegorov" <viy@pirmabanka.lv>
To: pgsql-sql@postgresql.org
Subject: Re: use of geometric types in select ?
Message-ID: <20030301083730.GA9377@pirmabanka.lv>
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References: <3E5E7E29.58D19347@cybernet.be>
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* dhoubrechts <dhoubrechts@cybernet.be> [01.03.2003 03:32]:
> I create a db : createdb geo
> I log into the db :  psql geo
> I create a table named poly :
> geo=3D# create table poly (parc varchar(15), graphic polygon);
>=20
> I populate the table :=20
> 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)');
>=20
> Now I would look if the first polygon overlaps the second using the
> varchars for retriving the poly.
> I could do it so :
> geo=3D# 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=3D# select graphic::polygon  from poly where parc=3D'A52' && select
> graphic::polygon from poly where parc=3D'A135';

Something like this:
select (g1.graphic && g2.graphic) from poly g1, poly g2
where g1.parc =3D 'A52' and g2.parc =3D 'A135';

--=20

Victor Yegorov

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