Abstract: Mapping relational databases is a programming technique that enables developers to interact with the database using objects, which are instances of classes defined in a specific programming language.  Objectives: This paper propose a scientific method based on several rules in order to transform the logic layer of a relational database into an object model formalized in a class diagram. Prior Work: This research is based on C.J. Date logic and relational approach on modelling relational databases. Approach: We are using the high-level Microsoft C# object-oriented programming language in order to implement the object model of a classic transactional database employing a set of rules and a specific library for serializing collections of objects for a dedicated (MongoDB) persistence layer, Results: the JSON serialized form of the objects is further used to generate new instances according to the business application layer. Implications: The back & forward transformations without information loss by serializing and deserializing objects according to a predefined data scheme validates the methodology proposed by this paper. Value: The importance of our research resides in the plenitude of source code utilized for exemplifying our methodology and the diversity of real-life situations that might benefit of our research in terms of efficiency and consistent data management.