What is Data Normalisation?

885    Asked by LillianHart in Business Analyst , Asked on Nov 5, 2019
Answered by Kaushik Chandra

Database normalization is the method of organization of data in order to decrease the redundancy and irregularities within the database. We have diverse Normalisation forms in SQL like – First Normal Form, Second Normal Form, Third Normal Form, and BCNF.

a. 1NF (First Normal Form) - According to First Normal Form, a column cannot have multiple values; each value in the columns must be atomic.

b. 2NF- A table to be 2NF, it must follow 1NF and there should be no column that is dependent on the primary key.

c. 3NF- A table to be 3NF, it must follow 2NF and each non-prime attribute should be dependent on the primary key.

For each functional dependency, X -> Y, either X should be the super key or Y should be the prime attribute of the table.

d. BCNF- BCNF is the most advanced or stricter version of 3NF.

For each functional dependency X -> Y, X should be the super key to be BCNF.



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