In a database whose entries contain values organized in categories, a first query is performed that includes input query values respectively associated with at least some of the categories and that seeks entries whose values match each input query value. Upon finding no entries, a category whose input query value to eliminate is identified. A second query is performed that includes the input query values except for the identified at least one category. The second query seeks any of the entries whose values match each of the input query values of the second query and that has no specified value for the identified at least one category. A data structure is configured to indicate an order that at least some of several categories will be eliminated when generating a new query after a previous query does not result in a match among entries of a database.