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From: dhoubrechts <dhoubrechts@cybernet.be>
X-Newsgroups: comp.databases.postgresql.sql
Subject: use of geometric types in select ?
Date: Thu, 27 Feb 2003 22:07:53 +0100
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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';

Thanks for help
Didier.