Home arrow Site Administration arrow Page 5 - Database Normalization

Fourth Normal Form (4NF) and Fifth Normal Form (5NF) - Administration

Put simply, normalization is an attempt to make sure you do not destroy true data or create false data in your database. Errors are avoided by representing a fact in the database one way, one time, and in one place. Duplicate data is a problem as old as data processing. Efficient and accurate data processing relies on the minimizing redundant data and maximizing data integrity. Normalization and the Normal Forms (NF) are efforts to achieve these two core objectives of data processing. This article will examine the concept of normalization in-depth.

  1. Database Normalization
  2. First Normal Form (1NF)
  3. Second Normal Form (2NF)
  4. Third Normal Form (3NF) and BCNF
  5. Fourth Normal Form (4NF) and Fifth Normal Form (5NF)
  6. Conclusion
By: David Fells
Rating: starstarstarstarstar / 125
June 16, 2004

print this article



Fourth Normal Form (4NF) and Fifth Normal Form (5NF)

Fourth normal form requires that a table be BCNF and contain no multi-valued dependencies. 4NF solves the problem of multivalued dependencies, which we would encounter with our above Sales table when a customer purchased multiple products with a single order - we would have numerous rows that were dependent on one another without any clear definition of that dependency in the table.

Fifth normal form, also known as join-projection normal form (JPNF), states that no non-trivial join dependencies exist. 5NF states that any fact should be able to be reconstructed without any anomalous results in any case, regardless of the number of tables being joined. A 5NF table should have only candidate keys and it's primary key should consist of only a single column.

The problem with these forms is the size of the joins that are required to reconstruct any non-trivial data.We can rely on views and procedures to simplify them but the underlying data still ends up very complex. There are also performance issues to consider - which is why 4NF and 5NF are often academic. In most cases, 3NF (or BCNF) are ideal.

>>> More Site Administration Articles          >>> More By David Fells

blog comments powered by Disqus
escort Bursa Bursa escort Antalya eskort


- Coding: Not Just for Developers
- To Support or Not Support IE?
- Administration: Networking OSX and Win 7
- DotNetNuke Gets Social
- Integrating MailChimp with Joomla: Creating ...
- Integrating MailChimp with Joomla: List Mana...
- Integrating MailChimp with Joomla: Building ...
- Integrating MailChimp with Joomla
- More Top WordPress Plugins for Social Media
- Optimizing Security: SSH Public Key Authenti...
- Patches and Rejects in Software Configuratio...
- Configuring a CVS Server
- Managing Code and Teams for Cross-Platform S...
- Software Configuration Management
- Back Up a Joomla Site with Akeeba Backup

Developer Shed Affiliates


Dev Shed Tutorial Topics: