[postgis-users] clip polygons

[Francisco Salas]

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] En nombre de Marta Debolini
Enviado el: lunes, 14 de enero de 2013 12:01 p.m.
Para: 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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