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

[Michal Zimmermann]

Thanks for the answers guys! I guess the data is ok, I was given them
at the university which had bought it from the GIS company, that's why
I trust this data source. Also when I try selecting the disctricts
with ArcMap, it works (not with QGIS, though!).
Sandro, would you be so kind and share some thoughts on PostGIS
Topology? As I understood, it is a completely new feature of v2,
right? What are the benefits?

On 10/10/12, Sandro Santilli <strk at keybit.net> wrote:
> On Wed, Oct 10, 2012 at 10:27:42AM +0200, Michal Zimmermann wrote:
>> 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.
>
> Try ST_Covers, which includes the boundaries.
>
> PS: yours is the perfect use case for PostGIS Topology !
>
> --strk;
>
>  http://www.cartodb.com - Map, analyze and build applications with your
> data
>
>                                        ~~ http://strk.keybit.net
>
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-- 
Michal Zimmermann (zimmi)
WWW: http://www.zimmi.cz