Using ontologies for SQL query reformulation

In this paper we present two ontological approaches for SQL query reformulation in order to help the user in his search when his initial query doesn´t return any result. The first approach is a query expansion approach based on different refinement types. This approach generates a set of queries satisfying the user´s intention or detects the reason of failure. The second one is a join detection approach to eventually add all missed constraints in each generated query.