On Directly Mapping Relational Databases to RDF and OWL
Mapping relational databases to RDF is a fundamental problem for the development of the Semantic Web. The authors present a solution, inspired by draft methods defined by the W3C where relational databases are directly mapped to RDF and OWL. Given a relational database schema and its integrity constraints, this direct mapping produces an OWL ontology, which, provides the basis for generating RDF instances. The semantics of this mapping is defined using Datalog. Two fundamental properties are information preservation and query preservation. They prove that their mapping satisfies both conditions, even for relational databases that contain null values. They also consider two desirable properties: monotonicity and semantics preservation.