PostGIS is an open source spatial database extender for PostgreSQL. It equals or surpasses proprietary alternatives, allowing you to create location-aware queries with just a few lines of SQL code, and provides a back-end for mapping applications with minimal effort.
PostGIS in Action teaches readers of all levels to write spatial queries that solve real-world problems. It first gives you a background in vector-based GIS and then quickly moves into analyzing, viewing, and mapping data.