Database modeling with Object Relationship Schema

Entity Relationship (ER) model for database design was developed by Peter Chen of MIT in 1976. This is an intuitive and conceptual representation of the data model. It is normally represented as an Entity Relationship Diagram (ERD), which is a graphical representation of the ER model. From this ERD, the Entity Relationship Schema (ERS) for the database shows the tables, their associated attributes, primary keys, and the relationships between the tables. A relational database model differs from hierarchical and network models by requiring explicit linkage of the related tables which is done by using foreign keys. It is the most widely used model because of its simplicity in representing and querying data. This research examines the ERS and suggests an augmented schema termed, in this research, as the Object Relationship Schema (ORS), with addition of new constructs to the ERS. Today, the resources required for the development of a database using a relational database management system are often measured by subjective criteria. The ORS is an objective and quantitative method to measure the database development effort, thus enabling one to apply appropriate resources towards developing, testing and maintaining the database. The improved constructs of the ORS are presented with an example for clarifying important design and implementation concepts.