An embodiment of the invention comprises a method and apparatus for structuring, storing and retrieving data in database systems utilizing relational objects referred to as qualifiers. Catalog data are segregated into one or more primary tables (e.g., main tables), one or more lookup tables, and one or more qualified lookup tables following a predefined set of categories and a taxonomy. Qualified lookup tables comprise a special type of fields referred to as qualifiers. Searches are conducted in embodiments of the invention by determining a set of lookup fields, performing a lookup in one or more lookup tables, and retrieving data values which include association values with records that belong to one or more primary tables. The qualifiers are then used to narrow the search space by selecting only those values that satisfy the selection criteria with regard to the qualifiers. In embodiments of the invention, only a small set in the primary table are traversed to retrieve eligible records.