Rules for Migrating from Entity Relationship (ER) Diagrams to Object Relationship (OR) Diagrams
In this paper, we provide detailed mapping rules (a methodology) to convert an ER schema into an object relationship (OR) schema. The mapping rules are presented in a manner that will keep as much of the semantics of the database intact, in order to smoothen the important step of data migration from an ER schema to an OR schema. This OR schema should also serve as a conceptual design tool for object-oriented data models, very much like the ER diagrams are a conceptual design tool for relational databases. Since we are mainly discussing the conversion from an ER model to an OR model, we are limiting the discussion in this paper to the structural aspects of the OR model.