SPARQL to SQL

Semantics Preserving SPARQL-to-SQL Query Translation for Optional Graph Patterns "...we proposed: (1) an efficient algorithm, BGPtoSQL, that generates an SQL query equivalent to an input SPARQL basic graph pattern to be evaluated over the triple store, and (2) a generic query translation strategy and an efficient algorithm, SPARQLtoSQL, that translates an input SPARQL query with a basic graph pattern or an optional graph pattern to an equivalent SQL query. To our best knowledge, our algorithmic solution for the optional graph pattern query mapping problem is the first published in the literature."