6-+Normalization

6-+Normalization - NORMALIZATION Douglas Havelka Miami...

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Unformatted text preview: NORMALIZATION Douglas Havelka Miami University The process of evaluating and designing table structures to minimize data redundancies, thereby reducing the likelihood of data anomalies. A process for assigning attributes to tables based on the concept of determination. Process involves a set of stages or levels referred to as “normal forms.” Higher is better 1NF, First normal form 2NF, Second normal form 3NF, Third normal form BCNF, Boyce-Codd normal form 4NF, Fourth normal form 3NF is the goal for most business DBs. Cost of normalization ↑ NF → ↑ joins → ↑ processing Denormalize: ↓ NF → ↑ Performance → ↑ % Anomalies GOAL: ‘WELL-FORMED RELATIONS’ 1 Table, 1 Subject 1 Data item, 1 Table (except keys) All non-key attributes depend on the PK … the whole PK and nothing but the PK NORMAL FORMS: RULES / CHARACTERISTICS 1NF: table format, no repeating fields, PK identified 2NF: 1NF and no partial dependencies 3NF: 2NF and no transitive dependencies NORMAL FORMS: RULES /...
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This note was uploaded on 04/01/2012 for the course MIS 245 taught by Professor Havelka during the Spring '12 term at Miami University.

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6-+Normalization - NORMALIZATION Douglas Havelka Miami...

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