Intro to DBMS

Important Points Of Normal Forms

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

Important points about normal form are given below


  • 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 such as 2NF, 3NF, BCNF, 4NF, and 5NF.


  • 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.


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

  • Start checking from the highest normal form (i.e., 5NF) because if the 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).


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