Business Intelligence Dictionary: Database Normalization And Normal Forms | NSBI
Optimization has always been a priority for business and database optimization is not an exclusion. Relational Database optimization is often related to a process called Normalization.
Normalization | Definition
Normalization is a process of optimization of a relational database in terms of data redundancy by partitioning data in different tables and applying relationships between them. This is achieved by correct assignment of primary keys and foreign keys across the fields.
The extent of normalization is also described by the so called Boyce-Codd Normal Forms.
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Boyce-Codd Normal Form 1 | Definition & Example
Rule says: Each field is atomic, it cannot be further broken into smaller entities.
Boyce-Codd Normal Form 2 | Definition & Example
Rule says: Each field is fully and uniquely identified by a Primary Key.
Example: "National ID" uniquely identifies John as a person, so this field should be the table Primary Key.
Boyce-Codd Normal Form 3 | Definition & Example
Rule says: Primary Key is not uniquely identified by any non Primary Key field.
Example: You cannot determine John's National ID by knowing his Name and Birth Place. There are many with this name born in Texas.
Normal Form 3 is the most widely used one. Normal Forms 4 and 5 are seldom achieved, so an example will be out of scope for them.
Boyce-Codd Normal Form 4 | Definition
Rule says: Each multi-value dependency is identified by a Primary key.
Boyce-Codd Normal Form 5 | Definition
Rule says: Each join is implied by the Primary Key.
See a sample visualization of a normalized relational schema:
Image Coutesy: www.nationalvetcontent.edu.au