[postgis-users] clip polygons

[Martin Davis]

Correct.  See http://postgis.net/docs/manual-2.0/ST_Intersection.html

On 1/14/2013 5:14 PM, Tim-Hinnerk Heuer wrote:
>
> I think Nicolas is more correct. St_Intersection sounds like a 
> function that gets a geometry while St_Intersects returns a Boolean.
>
> On Jan 15, 2013 6:24 AM, "Francisco Salas" <fsalas at pinar.geocuba.cu 
> <mailto:fsalas at pinar.geocuba.cu>> wrote:
>
>     Martha ,
>
>     I think that you must use in the select sentence
>     st_intersects(a.the_geom, b.the_geom) as the_geom , instead of
>     a.the_geom
>
>     Francisco Salas
>
>     *De:*postgis-users-bounces at lists.osgeo.org
>     <mailto:postgis-users-bounces at lists.osgeo.org>
>     [mailto:postgis-users-bounces at lists.osgeo.org
>     <mailto:postgis-users-bounces at lists.osgeo.org>] *En nombre de
>     *Marta Debolini
>     *Enviado el:* lunes, 14 de enero de 2013 12:01 p.m.
>     *Para:* postgis-users at lists.osgeo.org
>     <mailto:postgis-users at lists.osgeo.org>
>     *Asunto:* [postgis-users] clip polygons
>
>     Hi,
>     I am a new postgis user, so sorry if my request seems trivial for
>     someone.
>
>     I have to clip a polygon with another polygon file. I was used to
>     do this operation with the simple comand "clip" in GRASS or QGIS.
>     How can I do the same operation in postgis? I tried with
>     sy_intersect, but it takes also the polygons outside my area,
>     which simply intersect the border.
>     The request I wrote is:
>
>
>     CREATE TABLE w_md.x
>     AS (SELECT area, a.the_geom
>         FROM oc a, co b
>         WHERE st_intersects(a.the_geom, b.the_geom));
>
>         ALTER TABLE w_md.x_1999 ADD column ggid1 serial;
>          ALTER TABLE w_mdi.x_1999 ADD PRIMARY KEY (ggID1);
>
>     Thank you for your help,
>
>     Marta
>
>
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