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In QGIS, I can't seem to find a way to define the features that I want to label using a SQL query? Is this possible?
For example, I downloaded the OSM Natural shapefiles, and a lot of those features have no values in their "name" field. I would like to display all features, but only label those features where NAME <> "". The same concept could be applied to roads, where TYPE = "Motorway".
In the image below, I want all polygons visible, but don't want to label the 3 polys on the right.
You can now label features using an expression in version 1.8, something like this:
CASE WHEN NOT "NAME" IS NULL THEN "Name" END
or
CASE WHEN "TYPE" = 'Motorway' THEN "Name" END
Expression is invaild that is because I don't have those columns in layer
You can remove the text 'Label' from "Default Label" option in labeling dialog.
(Or use new labeling.)
There is no SQL for labels yet (but you don't need it in this case).
You can select the option in Labels Properties and only label 'selected features'
