DATABASE DESIGN Logical Database Design and the Relational Model DOCX

Title	DATABASE DESIGN Logical Database Design and the Relational Model
Author	Rvn Flores
Pages	1
File Size	109.5 KB
File Type	DOCX
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DATABASE DESIGN Logical Database Design and the Relational Model Normalization - Is a formal process for deciding which attributes should be grouped together in a relation. - Is the process of successively reducing relations with anomalies to produce smaller, well- structured relations. Following are some of the main goals of normalization: 1. Minimize data redundancy, thereby avoiding anomalies and conserving storage space. 2. Simplify the enforcement of referential integrity constraints. 3. Make it easier to maintain data (insert, update and delete). 4. Provide a better design that is an improved representation of the real world and a stronger basis for future growth. Steps in Normalization A normal form is a state of a relation that results from applying simple rules regarding functional dependencies for relationships between attributes to that relation. 1. First normal form- Any multivalued attributes (also called repeating groups) have been removed, so there is a single value (possibly null) at the intersection of each row and column of the table. 2. Second normal form – Any partial functional dependencies have been removed (i. e., nonkeys are identified by the whole primary key). 3. Third normal form- Any transitive dependencies have been removed (i. e., nonkeys are identified by only the primary key). 4. Boyce- Codd normal form – Any remaining anomalies that resukt from functional dependencies have been removed (because there was more than one primary key for the same nonkeys). 5. Fourth normal form – Any multivalued dependencies have been removed. 6. Fifth normal form – Any remaining anomalies have been removed. Functional Dependencies and Keys Functional dependency- A constraint between two attributes in which the value of one attribute is determined by the value on another attribute. Common examples of functional dependencies are as follows: Determinant- The attribute on the left- hand side of the arrow in a functional dependency. Candidate key- An attribute, or combination of attributes, that uniquely identifies a row in a relation. A candidate key must satisfy the following properties: 1 Database Management System (DBMS) Normalization Prepared by: kapetalbo2013...