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Normalization
(Publish Date: 2008-9-8 1:37pm, Total Visits: 792, Today: 1, This Week: 3, This Month: 3)

Normalization refers to the process of restructuring tables to eliminate design problems. Normalizing your tables removes redundant data, makes it possible to access data more flexibly, and eliminates the possibility that inappropriate modifications will take place that make the data inconsistent. Normalization of a complex table often amounts to taking it through a process of decomposition into a set of smaller tables. This process removes repeating groups within rows and then removes duplicate data within columns.

  • A table is in first normal form (1NF) if it contains no repeating groups within rows.

  • A table is in second normal form (2NF) if it is in 1NF and every non-key value is fully dependent on the primary key value. The latter constraint means that a non-key value cannot depend only on some columns of the primary key.

  • A table is in third normal form (3NF) if it is in 2NF and every non-key value depends directly on the primary key and not on some other non-key value.