A Hybrid Query Language for the Extended Entity-Relationship model

We present the hybrid query language HQL/EER for an Extended Entity-Relationship model. As its main characteristic, this language allows a user to freely mix graphical and textual formulation of a query. We demonstrate the user-friendliness of this query language by means of examples, and show how syntax and semantics of this language are formally de ned using programmed graph rewriting systems. Although we present the language in the context of the EER model, the concept of hybrid languages is applicable in the context of other database models as well.