Representing and querying conceptual graphs with relational database management systems is possible.

This is an experimental study on the feasibility of maintaining medical concept dictionaries in production grade relational database management systems (RDBMS.) In the past, RDBMS did not support transitive relational structures and had therefore been unsuitable for managing knowledge bases. The revised SQL-99 standard, however, may change this. In this paper we show that modern RDBMS that support recursive queries are capable of querying transitive relationships in a generic data model. We show a simple but efficient indexed representation of transitive closure. We could confirm that even challenging combined transitive relationships can be queried in SQL.