A query and display interface has been developed between the GRASS geographic information system and the SQL-based ORACLE relational database management system (DBMS) . This interface enables multiple non-spatial attributes of GRASS map features to be maintained with the DBMS. GRASS alone is capable of storing only one attribute per feature. The interface allows the user to provide both spatial (GRASS) and non-spatial (SQL) selection criteria for any query. Spatial selection methods include picking items from the GRASS map with a mouse, and specifying areas of interest with user-drawn (via a mouse) polygons and transects. The results of the combined query are displayed both graphically (the selected GRASS map features are highlighted in a graphics window) and textually (the DBMS attribute data are shown in a text display window). Options include creating reclassified maps based on the DBMS output, and updating the attributes retrieved by a query.
