Database Normalisation

This is an important concept one must know when dealing with databases. This is something which is quite often asked in Interviews.

Database  Normalization is a technique of decomposing data in a table. The main Intention to perform Normalization is to remove Data Redundancy and to ensure that there is uniqueness and consistency across the table.

By performing Normalization we resolve Issues of Insertion, Updation and Deletion. In case we have a table which is not Normalized, then there is a possibility that we might have two rows which are similar. And if we want to delete a particular row, Instead of performing one delete operation, we have to do it twice. This decreases the efficiency and multiplies the overhead cost. Since we are literally doubling the operations we perform.

In Order to overcome this, there are Normalization Rules available. And in case a table follows these rules, then the database can be called Normalized.

There are 4 major Normalization Rules-

  1. First Normal Form (1NF)
  2.  Second Normal Form (2NF)
  3. Third Normal Form (3NF)
  4.  Boyce and Codd Normal Form (BCNF)

 

These rules will be explained later!

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