SPATIAL SQL - A QUERY AND PRESENTATION LANGUAGE

Recently, attention has been focused on spatial databases, which combine conventional and spatially related data, such as Geographic Information Systems, CAD/CAM, or VLSI. A language has been developed to query such spatial databases. It recognizes the significantly different requirements of spatial data handling and overcomes the inherent problems of the application of conventional database query languages. The spatial query language has been designed as a minimal extension to the interrogative part of SQL and distinguishes from previously designed SQL extensions by 1) the preservation of SQL concepts, 2) the high-level treatment of spatial objects, and 3) the incorporation of spatial operations and relationships. It consists of two components, a query language to describe what information to retrieve and a presentation language to specify how to display query results. Users can ask standard SQL queries to retrieve nonspatial data based on nonspatial constraints, use Spatial SQL commands to inquire about situations involving spatial data, and give instructions in the Graphical Presentation Language GPL to manipulate or examine the graphical presentation.