Normalization

What is Normalization?
Database normalization is a data design and organization process applied to data structures based on rules that help building relational databases. In relational database design, the process of organizing data to minimize redundancy is called normalization. Normalization usually involves dividing a database into two or more tables and defining relationships between the tables. The objective is to isolate data so that additions, deletions, and modifications of a field can be made in just one table and then propagated through the rest of the database via the defined relationships.


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Author: sangeetha02 Mar 2009 Member Level: Gold   Points : 2

The process of taking a raw database and breaking it into logical units called tables. This process is referred to as normalization. The normalization process is used by database developers to design databases in which it is easy to organize and manage data while ensuring the accuracy of data throughout the database.

Normalization is a process of reducing redundancies of data in a database. Normalization is a technique that is used when designing and redesigning a database. Normalization is a process or set of guidelines used to optimally design a database to reduce redundant data.

The Raw Database
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A database that is not normalized may include data that is contained in one or more different tables for no apparent reason. This could be bad for security reasons, disk space usage, speed of queries, efficiency of database updates, and, maybe most importantly, data integrity. A database before normalization is one that has not been broken down logically into smaller, more manageable tables.

Logical Database Design
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Any database should be designed with the end user in mind. Logical database design, also referred to as the logical model, is the process of arranging data into logical, organized groups of objects that can easily be maintained. The logical design of a database should reduce data repetition or go so far as to completely eliminate it. After all, why store the same data twice? Naming conventions used in a database should also be standard and logical.

Data Redundancy
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Data should not be redundant, which means that the duplication of data should be kept to a minimum for several reasons. For example, it is unnecessary to store an employee's home address in more than one table. With duplicate data, unnecessary space is used. Confusion is always a threat when, for instance, an address for an employee in one table does not match the address of the same employee in another table. Which table is correct? Do you have documentation to verify the employee's current address? As if data management were not difficult enough, redundancy of data could prove to be a disaster.

The following are the three most common normal forms in the normalization process:

The first normal form

The second normal form

The third normal form

The First Normal Form
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The objective of the first normal form is to divide the base data into logical units called tables. When each table has been designed, a primary key is assigned to most or all tables.

The Second Normal Form
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The objective of the second normal form is to take data that is only partly dependent on the primary key and enter that data into another table.

The Third Normal Form
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The third normal form's objective is to remove data in a table that is not dependent on the primary key.

Benefits of Normalization
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Normalization provides numerous benefits to a database. Some of the major benefits include the following :

1.Greater overall database organization
2.Reduction of redundant data
3.Data consistency within the database
4.A much more flexible database design
5.A better handle on database security









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