SQL/EER—syntax and semantics of an Entity-Relationship-based query language

摘要

This paper presents the high-level query language SQL/EER for an extended Entity-Relationship model (EER model). SQL/EER directly supports all the concepts of the EER model and takes into account well-known features that are integral part of contemporary query languages, e.g. arithmetic and aggregate functions.In contrast to usual descriptions of query languages, we give SQL/EER a complete formal specification of syntax and semantics. The syntax is defined by using an attribute grammar which fixes the context-free structure and the context-sensitive rules. The operational semantics is defined by formally translating SQL/EER queries into queries of an existing, semantically well-defined calculus. The attribute grammar is extended to cover this translation, too.The query language SQL/EER is used in a database design environment. In this context, the formal specification of its syntax and the semantics has been used to implement a syntax-directed editor and a query interpreter for SQL/EER.