[WEBINAR] The New Normal: Dealing with the Reality of an Unsecure World

Fourth Normal Form (4NF)

Definition - What does Fourth Normal Form (4NF) mean?

Fourth normal form (4NF) is a level of database normalization where there are no non-trivial multivalued dependencies other than a candidate key.

It builds on the first three normal forms (1NF, 2NF and 3NF) and the Boyce-Codd Normal Form (BCNF). It states that, in addition to a database meeting the requirements of BCNF, it must not contain more than one multivalued dependency.

Techopedia explains Fourth Normal Form (4NF)

A multivalued dependency is best illustrated using an example. In a table containing a list of three things - college courses, the lecturer in charge of each course and the recommended book for each course - these three elements (course, lecturer and book) are independent of one another. Changing the course’s recommended book, for instance, has no effect on the course itself. This is an example of multivalued dependency: An item depends on more than one value. In this example, the course depends on both lecturer and book.

Thus, 4NF states that a table should not have more than one of these dependencies. 4NF is rarely used outside of academic circles.

Techopedia Deals

Connect with us

Techopedia on Linkedin
Techopedia on Linkedin
"Techopedia" on Twitter

Sign up for Techopedia's Free Newsletter!

Email Newsletter

Join thousands of others with our weekly newsletter

Free Whitepaper: The Path to Hybrid Cloud
Free Whitepaper: The Path to Hybrid Cloud:
The Path to Hybrid Cloud: Intelligent Bursting To Amazon Web Services & Microsoft Azure
Free E-Book: Public Cloud Guide
Free E-Book: Public Cloud Guide:
This white paper is for leaders of Operations, Engineering, or Infrastructure teams who are creating or executing an IT roadmap.
Free Tool: Virtual Health Monitor
Free Tool: Virtual Health Monitor:
Virtual Health Monitor is a free virtualization monitoring and reporting tool for VMware, Hyper-V, RHEV, and XenServer environments.
Free 30 Day Trial – Turbonomic
Free 30 Day Trial – Turbonomic:
Turbonomic delivers an autonomic platform where virtual and cloud environments self-manage in real-time to assure application performance.