Normalization in SQL is the process in which the data is organized in the database. It is used to minimize repetition from the various relations in the database. It is also used in order to eliminate anomalies like insertion, deletion, and update in the tables. It helps in dividing a large table into multiple small normalized tables that are connected and linked using a relationship to reduce redundancy.
The normal forms (NF) can be widely classified into four types: 1NF, 2NF, 3NF, and BCNF (Boyce Codd Normal Form).
- A relation is considered in 1NF only if each domain attribute consists of a single atomic or indivisible value. It is a very significant property of a relationship that is available in the RDBMS.
- A relation is in 2NF only if it is in 1NF as well as all the non-key attributes in the tables are dependent on the table’s primary key. This form applies to those relations that are connected using composite keys. The relation of the tables is linked with a key that is composed of more than one attribute.
- A relation is in 3NF if and only if it is in 2NF and there is no transition dependency. This is used in order to remove anomalies that are caused due to the transitive dependency.
- BCNF is a normal form wherein any functional dependency-based redundancy is removed. It is a stronger version of the 3NF. It accounts for all candidate keys that are in relation.
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