Normalization the process of organizing data in a database that includes creating tables and establishing relationships between the tables.

The process is used to help eliminate redundant data.

Five normalization forms (NF's):

In this article, we are going to cover first three normaizations, which are most frequently used.


SQL Server - Normalization - First Normal Form (1NF)

Database Normalization - First Normal Form (1NF)

The first normal form means the data is in an entity format, which means the following conditions have been met:

  • Eliminate repeating groups in individual tables
  • Create separate table for each set of related data
  • Identify each set of related data with primary key

Do not use multiple fields in a single table to store similar data. 


SQL Server - Normalization - Second Normal Form (2NF)

Database Normalization - Second Normal Form (2NF)

The second normal form ensures each attribute describes the entity

  • Create separate tables for sets of values that apply to multiple records
  • Relate these tables with a foreign key

Records should not depend on anything other than a table’s primary key, including a compound key if necessary. 


SQL Server - Normalization - Third Normal Form (3NF)

Database Normalization - Third Normal Form (3NF)

The third normal form checks for transitive dependencies.

  • Eliminate fields that do not depend on the key

Values that are not part of the record’s key do not belong in the table .

In general if the contents of a group of fields apply to more than a single record, put those fields in a separate table.