1. A method, in a data processing system, for mapping objects and object-relationships in an object model to a nested relational database, comprising: obtaining entity metadata constructs for an object relational mapping framework, the entity metadata constructs mapping fields in entities of an object model to fields in a data table of the nested relational database and identifying relationships between entities in the object model; obtaining a nested relational data model of the nested relational database, the nested relational data model specifying tables and sub-tables of the nested relational database; mapping tables and sub-tables of the nested relational database to a plurality of separate entities of the object model, wherein at least one parent table is mapped to at least one top-level entity and at least one sub-table is mapped to at least one sub-entity of the at least one top-level entity; and accessing data in the nested relational database using the plurality of separate entities, wherein the mapping is performed without normalizing the data of the tables and sub-tables of the nested relational database to a non-nested representation.