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Data Normalization

IT Notes → Database @ December 22, 2020

  • Denormalization is the process of attempting to optimize the read performance of a database by adding redundant data or by grouping data.
  • First Normal Form means a form with a primary key, no row-ordering or column ordering as an intrinsic and meaningful aspect of the view and no nullable fields.
  • 1NF table is in Second Normal Form if and only if all its non-prime attributes are functionally dependent on the whole of a candidate key. Non-prime attributes do not form part to any candidate key. When 1NF table has no composite candidate keys it automatically becomes 2NF.
  • 2NF table is in Third Normal Form if and only if all its non-prime attributes are directly dependent on every candidate key.
  • Anomalies: Updation has occurred in linked table but foreign key in linking table has not been updated. This creates updation and insertion anomalies. Deletion has occurred in linked table but foreign key in linking table has not been deleted. This creates deletion anomaly.

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