PostGIS and SpatiaLite offer a large number of spatial query operations, including buffers, intersections, and spatial joins. It’s really useful, especially when you’re still experimenting, to visualize your results without having to create a new spatial table, spatial view, or exporting to a shapefile or other GIS data format. Fortunately, there are several ways to do this, including at least three plugins for Quantum GIS: Fast SQL Layer, PostGIS Query Editor, and RT SQL Layer. In this blog post I will walk you through using Fast SQL Layer. Continue Reading »