Transforming an Entity - Relationship Model into an Object - Oriented Database Model Depending on the Role of Relationship

The Entity-Relationship (E-R) model is widely used not only to increase understanding between user and designer, but also to model the relationship of real world data appropriately when designing database system in many application areas. It should be then transformed into an Object-Oriented database model which gives good merits to represent and manipulate data efficiently. Therefore, a method of transforming an E-R model into an Object-Oriented database model should be studied, but without losing any semantics of concept for the E-R model. This paper not only deals with transformation rules taking as input the elements of E-R model and delivering the elements of an Object-Oriented database model, but also improves the concept of generalization and aggregation inheritance. The paper also presents a method of transformation of relationship depending on these rules. The proposed method that obtains Object-Oriented database schema from an E-R model with preserving the properties of the E-R model is shown with examples. The method presented is able to be used to the logical database design.