The Need for Normalization

The aim of normalization is to put the data into tables in its simplest forms. We normalize the relational database management system because of its following characteristics and features. They are: 1. It helps to minimize data redundancy i.e. there should not be any multivalued attributes. Moreover eliminating the repeating groups. 2. Helps to make database structure flexible. It means it could allow to add new data values and rows in a relation structure without reorganizing the database structure. 3. To make consistency of data throughout the database i.e. it should not suffer from anomalies as given below: a. Insert Anomaly – It occurs due to lack of data i.e. data items are scattered and are not linked to each other properly, then it could lead to strange situations. This kind of anomaly can cause serious damage to the database b. Update Anomaly – It occurs because of data redundancy i.e. same value occurs multiple times in a column. This leads to inefficiency. c. Deletion Anomaly - It leads to the loss of data from rows that are not stored anywhere in the database. This could result in loss of vital data. 4. It is easy to handle complex queries that are required by the users. 5. *On decomposition of a relation into smaller relations with fewer attributes on normalization the resulting relations whenever joined must result in the same relation without any extra rows. The join operations can be performed in any order. This is known as Lossless Join decomposition.* 6. *The smaller and manageable tables obtained on normalization should possess the following properties such as each row must be identified by a unique key, no repeating groups, homogenous columns, each column is assigned a unique name etc.* 7. To built a database where it is easy to access and manipulate data easily, quickly and efficiently without compromising the integrity of data in a storage.

It is necessary to ensure that all of our data structures in a relational database are able to be implemented efficiently. Let us consider a situation - for example Customer:

Customer Number
Name
Address
Phone Number
Item Purchased
Quantity
Price
The above situation can easily be implemented in a database table. However a customer may order several items and each customer database may order a different number of items. So it difficult for us to implement the data in a relational database since we are not aware of how many Order entries to allow.

Suppose we have the situation where most of our customer orders only a single item, several other customers are ordering 2 or 3 and one is ordering 20. In this case we have to allow for up to 20 orders in our table for every customer even though most of them are ordering only one product. This will increase the storage space of the data and is a very wasteful of space and would make the database perform very poorly. Thus it is necessary to normalize in order to increase its storage efficiency, data integrity along with faster accessing of information from the database tables.