Stephan, Well since you have a multipolygon, I think you have to do something like this
SELECT gid, name FROM (SELECT gid, name, (ST_Dump(the_geom)).geom As the_geom FROM table ) As thetable WHERE ST_NumInteriorRings(the_geom) > 0; I would have suggested just running ST_NumInteriorRings instead of the subselect, but I think ST_NumInteriorRings only looks at the first polygon in the MULTI set so you have to deconstitute it with ST_Dump into individual polygons. Your ST_nrings > 1 would also then work too. Hope that helps, Regina -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Stephan Holl Sent: Thursday, July 10, 2008 8:06 AM To: [email protected] Subject: [postgis-users] Finding polygones with 'holes' inside Hi, I like to accomplish the task of finding polygons with holes inside (the table is a MULTIPOLYGON). I tried to use ST_nrings, but I am not sure it this always only finds polygons with wholes inside or also islands, which should be also rings by definition. So a SELECT gid, name FROM table WHERE ST_nrings(the_geom) > 1; does not only find whole polygons, but also polygons with more than one polygon. PostGIS 1.3.3 with PG 8.3.3 Is there an option to identify 'holes' within polygons directly? Thanks Stephan _______________________________________________ postgis-users mailing list [email protected] http://postgis.refractions.net/mailman/listinfo/postgis-users ----------------------------------------- The substance of this message, including any attachments, may be confidential, legally privileged and/or exempt from disclosure pursuant to Massachusetts law. It is intended solely for the addressee. If you received this in error, please contact the sender and delete the material from any computer. _______________________________________________ postgis-users mailing list [email protected] http://postgis.refractions.net/mailman/listinfo/postgis-users
