DBMS Notes

Important Points Of Normal Forms

As we know normalization is used to remove the redundancy in database.  Types of normal forms are given below

Important points about normal form are given below

Point-01:

  • A relation in 5NF will always be in all other normal forms as 4NF, BCNF, 3NF, 2NF and 1NF. In the same way, a relation in 3NF will always be in 2NF and 1NF.
  • But keep in mind, a relation in 1NF may or may not be in other forms as 2NF, 3NF, BCNF, 4NF and 5NF.

Point-02:

  • 5NF is highest stricter than all other forms as 4NF, BCNF, 3NF, 2NF and 1NF. In the same way
  • 1NF is less strict than 2NF, 3NF, BCNF, 4NF and 5NF.

Point-03

Keep in mind, while finding the normal forms of any given relation,

  • Start checking from highest normal form (i.e. 5NF) because if given relation is found to be in 5NF, then it will surely be 4NF, BCNF, 3NF, 2NF and 1NF.
  • If the relation is not in 5NF, then start moving downwards to lower normal forms i.e. (4NF, BCNF, 3NF, 2NF and 1NF).

Point-04

  • In a relational database, at least a table will be in 1NF.
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