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):
4NF: Isolate Independent Multiple Relationships
5NF: Isolate Semantically Related Multiple Relationships
In this article, we are going to cover first three normaizations, which are most frequently used.
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.
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.
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.