Hi, > Date: Mon, 11 Jun 2012 10:45:07 +0200 > From: Peter Sch?rch <p.schue...@meierpartner.ch> > To: <qgis-user@lists.osgeo.org> > Subject: [Qgis-user] Field Calculator: dynamic calculations > Message-ID: > <3266F9F673EFF44BB345D5A707E32AC2919477@meiwed1.meierpartner.local> > Content-Type: text/plain; charset="iso-8859-1" > > Hi all, > How would I implement a dynamic calculation with the field calculator? With > dynamic I mean that the > result would change as values change in the input > fields. With a Shape file, the result field obviously only contains the > numerical result of any calculation and when the input changes I have to > retype and re-execute the calculation in the field calculator. > In other GIS-Systems I have used this would be called a query. > > Thanks for any input on this. > Peter
I guess some providers (PostGIS and Spatialite?) might have a feature that allows this, but otherwise I don't think it is currently possible, except for labelling. As I mentioned in another thread today, there was a discussion about implementing "virtual columns" using the same engine as the expression based labelling. See http://lists.osgeo.org/pipermail/qgis-developer/2011-July/015383.html You might want to look at helping implement it. Regards, Alister _______________________________________________ Qgis-user mailing list Qgis-user@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/qgis-user
