Rules of Data Normalization

2008-12-02
實務電腦

Rules of Data Normalization

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Eliminate Repeating Groups - Make a separate table for each set of related attributes, and give each table a primary key.
Eliminate Redundant Data - If an attribute depends on only part of a multi-valued key, remove it to a separate table.
Eliminate Columns Not Dependent On Key - If attributes do not contribute to a description of the key, remove them to a separate table.
Boyce-Codd Normal Form - If there are non-trivial dependencies between candidate key attributes, separate them out into distinct tables.
Isolate Independent Multiple Relationships - No table may contain two or more 1:n or n:m relationships that are not directly related.
Isolate Semantically Related Multiple Relationships - There may be practical constrains on information that justify separating logically related many-to-many relationships.
Optimal Normal Form - a model limited to only simple (elemental) facts, as expressed in Object Role Model notation.
Domain-Key Normal Form - a model free from all modification anomalies.

http://www.datamodel.org/NormalizationRules.html


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