Hi Carson, On Thu, 30. Sep 2010 at 13:18:46 +0100, Carson Farmer wrote: > http://www.carsonfarmer.com/?p=713 > and the RT Sql Layer plugin > > 1 - Is it possible to build a query where two (or more) layers are > > involved? Something like: > > > > SELECT a.* > > FROM a, b > > WHERE Contains(b, a)
and that simple case can be expressed as exists expression in the query builder (for postgres and spatialite). Create a layer from a and use following query string: exists (select * from b where contains(b.geom,a.geom)) Creating views is another option (but you still need a unique 32bit integer primary key for the feature ids, which might be hard to generate in some cases). Jürgen -- Jürgen E. Fischer norBIT GmbH Tel. +49-4931-918175-20 Dipl.-Inf. (FH) Rheinstraße 13 Fax. +49-4931-918175-50 Software Engineer D-26506 Norden http://www.norbit.de -- norBIT Gesellschaft fuer Unternehmensberatung und Informationssysteme mbH Rheinstrasse 13, 26506 Norden GF: Jelto Buurman, HR: Amtsgericht Emden, HRB 5502 _______________________________________________ Qgis-user mailing list Qgis-user@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/qgis-user