Posts tagged Normalization

For any application to use database and hence data effectively it is very important that data is organized properly. The most common problem for database is redundancy in data. If table has highly redundant data, that means for every operation (like insert, update or delete) it takes more effort to find correct record. And it can be even troublesome when we simply search for record and we get redundant results which is just waste of space and time. To overcome this problem of redundancy in data, a specific procedure is developed which is called “Normalization” . As we know, in RDBMSes (like SQL Server, Oracle, MySQL) data is stored based on relation. And this relations are used in process of normalization to reduce redundancy in data and hence improving overall performance of system.

Unfortunately, normalization is the process that can be used to properly arrange data is applied during very initial phase of database designing which is called logical modeling. But, most of the time when you realize that you have screwed up and have not properly optimized database it is already late. The concept of normalization was firstly introduced by E.F. Codd, who is known to us as an inventor of relational database management system. Actually he published a paper containing 12 rules to define what is relational database actually meant. All modern DBMSes follow these rules and if we consider while designing database, it can have significant effect later.

Concepts of normalization can be explained with following example. Consider following table which shows student details including chosen subject and advisor for that subject.

Un-Normalized Data

First Normalization (1NF) : It is very basic rule of normalization. It dis-allows multivalued attributes & composite attributes. So, above shown table has to be rearranged as shown below.

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