"D2R MAP is a declarative language to describe mappings between relational database schemata and OWL ontologies. The mappings can be used by a D2R processor to export data from a relational database into RDF.
The mapping process executed by the D2R processor has four logical steps:
1. Selection of a record set from the database using SQL
2. Grouping of the record set by the d2r:groupBy columns.
3. Creation of class instances and identifier construction.
4. Mapping of the grouped record set data to instance properties. "
Based on Jena 2.