[postgis-users] Select polygons within polygon with PostGIS 2.0

[Francois Hugues]

Hello,

I don't know how your differents layers has been made but your problem certainly rely on difference with boundaries even if there are very little different and just one point not into the county, your district will not be select.

If you want to correct that you could use a buffer (st_within(o.geom,st_buffer(k.geom,XX)) big enough to correct the little differences of the boundaries but not too big although you may select too many districts.

Hugues.


-------- Message d'origine--------
De: postgis-users-bounces at postgis.refractions.net de la part de Michal Zimmermann
Date: mer. 10/10/2012 10:27
À: postgis-users at postgis.refractions.net
Objet : [postgis-users] Select polygons within polygon with PostGIS 2.0
 
Hi to all,
I have a relation representing all the counties in my country and the
other one containing all the districts - e. g. each and every county
is composed of several districts. How do I select them with spatial
query? I tried with
select nazorp from kraje as k, orp_wgs as o WHERE ST_Within(o.geom,k.geom) AND
k.nazev = 'Liberecký' // name of the county

but had wrong results returned (well, they are probably not wrong,
they are just not what I expected them to be). ST_Within only returns
districts that don't share a boundary with the county, but I need to
get all the districts within the county. Is that possible? I haven't
found any built-in function suitable for my needs yet.

-- 
Michal Zimmermann (zimmi)
WWW: http://www.zimmi.cz
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