Standardizing and Interfacing Relational Databases Using Conceptual Graphs

In order to apply Conceptual Graphs to Relational Databases [Bo&al93], we developed the notion of sets associated to a CG, introduced built-in relations to express general conditions for joining relations, and then began to sketch the ability of a CG base to allow a uniform representation of schemata, data and queries in a Database. Using this formalism, we now show how to express nested selects, and how it is possible to process incomplete queries, helping the user to query the Database without precisely knowing its structure. As these first-level Database concepts may be uniformly represented using CGs, our centre of interest is now higher-level notions such as queries upon queries. CGs may be used to represent not only the basic Database concepts, but the entire Database, including Database management operations.