Max Egenhofer IEEE Transactions on Knowledge and Data Engineering 6 (1): 86-95, 1994.
Abstract
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 non-spatial
data based on non-spatial 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.
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Max Egenhofer
