Mechanisms are provided for mapping objects and object-relationships in an object-oriented programming language to a nested relational database. Entity metadata constructs for an object relational mapping framework are obtained, 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. A nested relational data model of the nested relational database is obtained, the nested relational data model specifying tables and sub-tables of the nested relational database. Tables and sub-tables of the nested relational database are mapped to a plurality of separate entities of the object model. Data in the nested relational database is accessed using the plurality of separate entities. The mapping is performed without normalizing the data of the tables and sub-tables of the nested relational database to a non-nested representation.