Describing relational data sources by means of ontologies constitutes the foundation of most of the semantic based approaches to data access and integration. In this work we introduce an automatic procedure for building ontologies starting from the integrity constraints present in the relational sources. The use of a conceptual model to describe relational data sources has been proved to be extremely useful to overcome many important data access problems. However, the task of wrapping relational data sources by means of ontology is mainly done manually. In this work we introduce an automatic...