Thursday, February 17, 2011

A brief note on Normalization Forms in Database

The First normal form (1NF) sets the basic rules for an organized database. These rules relate to firstly, Eliminate duplicative columns from the same database table. Secondly, To create separate tables for each group of related data and identify each row with a unique column or set of columns (the primary key). The Second normal form (2NF) further Handles the concept of removing duplicative data. Firstly, It must meet all the requirements of the first normal form. And then remove subsets of data that apply to multiple rows of a table and place them in separate tables. In addition we must create relationships between these new tables and their predecessors through the use of foreign keys. The Third normal form (3NF) goes one large step further. Firstly, it must meet all the requirements of the second normal form. And then, remove columns that are not dependent upon the primary key. And the fourth normal form (4NF) has one additional requirement other than meeting all the requirements of the third normal form. It is maintained that a relation is in 4NF if it has no multi-valued dependencies

No comments:

Post a Comment