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SPATIAL QUERY LANGUAGES: EXTENDED SQL vs. VISUAL LANGUAGES vs. HYPERMAPS

We compare the respective advantages and limitations of three different approaches for querying geographical data bases, namely extended SQL languages, visual languages and hypermaps. A sample database is defined, along with a typology of queries which is based on a minimal set of queries that a true geographic DBMS should be able to process. The principles of each of the three approaches are presented. Respective advantages and limitations are pointed out, based on the set of queries previously defined.