Mapping between ontologies and relational databases is
a necessity for realising the Semantic Web vision.
Most of the work concerning this topic has either (1) extracted an OWL schema using a
limited range of OWL modelling constructs from a relational
schema, or (2) extracted a relational schema from an OWL
schema, that represents as much as possible the OWL schema. By
contrast, we propose a general framework that maps between relational
databases and schemas expressed in OWL 2. In particular, we regard
the transformation from databases to ontologies as a two-phase
process. Firstly, convert the relational schema into an OWL schema,
and secondly enrich the
OWL schema with highly expressive axioms based on analysing the schema and the data
in the database. Testing our data analysis heuristics on a number of databases show that
they produce an OWL schema that includes more semantic information than found in the relational schema.