What's database normalization

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What's database normalization

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What's database normalization

  1. 1. Normalization is the process where a database is designed in a way that removes redundancies, and…. increases the clarity in organizing data in a database.
  2. 2. In easy English, it means take similar stuff out of a collection of data and place them into tables.
  3. 3. Keep doing this for each new table recursively and you'll have a Normalized database.
  4. 4. From this resultant database you should be able to recreate the data into it's original state if there is a need to do so.
  5. 5. Normalization of a Database is achieved by following a set of rules called 'forms' in creating the database.
  6. 6.  1st Normal Form or 1NF  2nd Normal Form or 2NF  3rd Normal Form or 3NF  BCNF (Boyce & Codd)  4NF  5NF
  7. 7. Each Column Type is Unique.
  8. 8. The entity under consideration should already be in the 1NF and all attributes within the entity should depend solely on the entity's unique identifier.
  9. 9. The entity should already be in the 2NF and no column entry should be dependent on any other entry (value) other than the key for the table. If such an entity exists, move it outside into a new table.
  10. 10. The database should be in 3NF and all tables can have only one primary key.
  11. 11. Tables cannot have multi-valued dependencies on a Primary Key.
  12. 12. There should be no cyclic dependencies in a composite key.

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