The linked data initiative brought new opportunities for building the next generation of Web applications. However, the full potential of linked data depends on how easy it is to transform data stored in relational databases into RDF (Resource Description Framework) triples. Recently, the W3C RDB2RDF working group proposed a mapping language, called R2RML, to specify mappings between relational schemas and RDF vocabularies. However, the specification of R2RML mappings is not an easy task. This paper therefore proposes a strategy to simplify the specification of R2RML mappings.