| Summary: | 碩士 === 國立中央大學 === 資訊管理學系 === 104 === Since the rise of object-oriented programming language, object-oriented system development get more and more attention. Consistency, completeness and correctness of the design class diagram will determine the system success or failure. Currently, entity relationship model and normalization technique for structured system design has developed clear principles and a process steps, but lack of complete discussion for object-oriented system design yet. This paper research object oreiented normalization theories through the object-oriented encapsulation, inheritance and polymorphism characteristics, proposed object-oriented principles of first to fourth normal form, and convert the principle into specific seven-step object-oriented design class diagram modeling process which will generate a normalized database, and provide a system operation architecture with object-oriented characteristics.
To complete class normalization study, considering class operation normalization based on the normalized steps of strustured system design, eliminating complex operation to prevent from overlapping functions is proposed in first object normal form. Eliminating common operation to prevent from cross-object-access operation is proposed in second object normal form. Eliminating resemble operation to meet inheritance and polymorphism characteristics is proposed in third object normal form. Eliminating multi-dependent operation to prvent from multivalued dependencies is proposed in fourth object normal form. According to above-mentioned, a clear and concise system design class modeling method is proposed.
Based on the above, the contribution are eliminating multivalue attribute, complex attribute and complex opeartion in the first step, eliminating part dependency, transitive dependency and common operation in the second step, eliminating resemble operation to meet inheritance and polymorphism characteristics in the third step, establishing Class to meet encapsulation characteristics in the fourth and fifth step, eliminating multivalue dependent attribute and multi-dependent operation in the sixth and seventh step, making system design with object-oriented characteristics, achieve consistency, completeness and correctness.
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