Revision with unchanged content. Relational.OWL is a technique to automatically convert a relational database into a Semantic Web representation, enabling Semantic Web applications to access data actually stored in relational databases using their own built-in functionality. Since this representation does not result in objects containing real semantics, we additionally show how to create mappings from the relational model to a target ontology using an arbitrary closed RDF query language. Using current Semantic Web techniques, a formerly relational data item, once converted to its Semantic Web representation, can neither be identified unambiguously, nor be backtracked to its original storage location in the relational database. We hence introduce a novel URI scheme for identifying not only databases, but also their schema and data components like tables or columns, giving us the possibility to specify the exact and identifying storage location of any data item in its original data source.