chapter 5 - part 2- 3-15 - CGS 2545 Database Concepts...

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CGS 2545: Database Concepts (Chapter 5) Page 1 Mark Llewellyn CGS 2545: Database Concepts Spring 2010 Chapter 5 – Logical Database Design And The Relational Data Model – Part 2 School of Electrical Engineering and Computer Science University of Central Florida Instructor : Dr. Mark Llewellyn [email protected] HEC 236, 407-823-2790 http://www.cs.ucf.edu/courses/cgs2545/spr2010
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CGS 2545: Database Concepts (Chapter 5) Page 2 Mark Llewellyn In general, the goal of a relational database design is to generate a set of relation schemas that create an accurate representation of the real-world situation that is being modeled. The design must also allow information to be stored without unnecessary redundancy, yet also allow for that information to be retrieved efficiently. A technique that can be used to identify this set of suitable relational schemas is called normalization . The process of normalization builds a set of schemas, each of which is in an appropriate normal form . Normalization is a bottom-up approach to database design that begins by examining the relationships between attributes. To determine if a relation schema is in one of the desirable normal forms, additional information is required about the real-world scenario that is being modeled. Most of this additional information is represented by a type of data dependency known as a functional dependency . Introduction To Normalization
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CGS 2545: Database Concepts (Chapter 5) Page 3 Mark Llewellyn Introduction To Normalization The process of normalization can be defined formally as: The process of normalization was first developed in the early 1970s by E.F. Codd. Normalization is most often performed as a series of tests on a relational schema to determine whether it satisfies or violates the requirements of a given normal form. Codd initially proposed three normal forms called first (1NF), second (2NF), and third (3NF). Subsequently, R. Boyce and Codd together introduced a stronger definition for third normal form called Boyce-Codd Normal Form (BCNF). All four of these normal forms are based upon the concept of a functional dependency. Higher normal forms that go beyond BCNF, such as fourth (4NF) and fifth (5NF), as well as several others, have also subsequently been introduced. These higher normal forms utilize other types of data dependencies and some of these apply to situations that are quite rare. We will concentrate only on the first four normal forms and not examine any of the higher normal forms.
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