Class normalization is a process that can be used to organize the structure of object schema to increase the cohesion of classes while minimizing the coupling between them. This research proposes a method to apply the rule of class normalization to class modeling during the object-oriented systems analysis and design process. A real-world case is presented to illustrate the concepts, application, and the advantages of using the proposed method. Utilizing this method in class modeling can help the system developer ensure the class diagram in third object normal form and thereby enhance the effectiveness of system development.

Object-Oriented analysis and design approach has become the mainstream of today¡¦s systems development technique. The Class Diagram in Unified Modeling Language (UML) is the major tool for modeling the class structure in the object-oriented system analysis and design process. Once the class diagram is constructed, class normalization needs to be performed to eliminate the anomalies for the designing a database. However, the detailed guideline for performing class normalization is lacking. Therefore, this study presents a class normalization methodology based on object normal forms proposed by Ambler (1996). Two real-world cases are presented to illustrate the concepts, application, and the advantages of using the proposed method. Using this methodology in class modeling will help system developers normalize the class design in advance, and thereby enhance the efficiency and effectiveness of system development.

Relational databases are the most popular databases used by enterprise applications to store persistent data to this day. It gives a lot of flexibility and efficiency. A process called database normalization helps make sure that the database is free from redundancies and update anomalies. In a Database-First approach to software development, the database is designed first, and then an Object-Relational Mapping (ORM) tool is used to generate the programming classes (data layer) to interact with the database. Finally, the business logic code is written to interact with the data layer to persist the business data to the database. However, in modern application development, a process called Code-First approach evolved where the domain classes and the business logic that interacts with the domain classes are written first. Then an Object Relational Mapping (ORM) tool is used to generate the database from the domain classes. In this approach, since database design is not a concern, software programmers may ignore the process of database normalization altogether. To help software programmers in this process, this thesis takes the theory behind the five database normal forms (1NF - 5NF) and proposes Five Class Normal Forms (1CNF - 5CNF) that software programmers may use to normalize their domain classes. This thesis demonstrates that when the Five Class Normal Forms are applied manually to a class by a programmer, the resulting database that is generated from the Code-First approach is also normalized according to the rules of relational theory.