How to Implement Fourth Normal Form
In this article I am going to explain how to Implement fourth normal form in SQL.
Introduction
Normalization is used to organize the content of table. Normalization is a technique which eliminate redundancy and inconsistent dependency of data from database. Normalization makes database more flexible.
Basic Goal of normalization
- Arrange data in database in to logical grouping.
- Eliminate redundancy of data, it means minimizing the duplicate data in database.
- Eliminate inconsistency of data.
Fourth Normal Form
For a table in fourth normal from it must be in Boyce codd normal form (BCNF) and it contain no multi value dependency.
Example
In this table data is in Boyce codd normal form but not in fourth normal form.
Table in Boyce codd normal form (BCNF) but not in Fourth Normal Form
Faculty |
Subject |
committee |
Vipendra |
SQL Server |
Placement |
Vipendra |
Oracle |
Placement |
Vipendra |
Java |
Placement |
Vipendra |
SQL Server |
Sport |
Vipendra |
Oracle |
Sport |
Vipendra |
Java |
Sport |
Deepak |
SQL Server |
Placement |
Deepak |
Oracle |
Placement |
Deepak |
Java |
Placement |
Deepak |
SQL Server |
Sport |
Deepak |
Oracle |
Sport |
Deepak |
Java |
Sport |
Now we divide this table in two different tables and these tables are in fourth normal form.
Table 1
Faculty |
Subject |
Vipendra |
SQL Server |
Vipendra |
Oracle |
Vipendra |
Java |
Deepak |
SQL Server |
Deepak |
Oracle |
Deepak |
Java |
Table 2
Faculty |
committee |
Vipendra |
Placement |
Vipendra |
Sport |
Deepak |
Placement |
Deepak |
Sport |