Normalization

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Normalization

Post  skyboard on Mon Oct 03, 2011 3:23 pm

The goal of normalization is to reduce data redundancy and data inconsistencies.

It is based on functional dependencies and decomposition of a table into a set of related tables that satisfy specific requirements. Those tables are called "normal forms"

Most common normal forms are:

First normal form (1NF):
a table in which the intersection of each row and column contains one and only one value
(there are no repeating groups)

Second normal form(2NF)
a table that is in 1NF and every non-primary-key attribute is fully functionally dependent to the primary key

Third normal form(3NF)
based on transitive dependency(if A -> B and B-> C, then C is transitively dependent on A through B)
A table that is in 2NF and in which no non-primary key attribute is transitively dependent on the primary key
Boyce-Codd normal form(BCNF)
Two primary key can decide other attributes





skyboard

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