by Raj Kumar

Created on: September 08, 2009

In simple terms, database is a software program to store, access and manage the data in an organized manner. There is a system which works behind the database and is called as database management system (DBMS). Actually the database can be assumed as an integral part of DBMS. If we just look at the feature of storing the data or information, there are other means through which data can be stored like Microsoft Excel spreadsheets, Word documents and flat text files. But they are neither well organized nor support most needed features like authentication, security permissions, quick data search based on customized criteria and controlled manipulations or transactions with accuracy, integrity and availability.

Database is built on a specific data model. Depending on the model used, database features and data services vary. Based on the model, database can be classified into hierarchal, network, relational and object model database management system. A database having hierarchal model has simple composition which looks similar to tree shaped nodal structure. But it is less flexible and restricts itself to one-to-many data storage relationships. Hierarchal model is used in specialized domain like Mobile technologies and data storage related to geographical information. Network model has more complex form of data storage structure as compared to hierarchal model. Network database supports many-to-many data relationships. Data access can be done using one of several paths. Both hierarchal and network model works on the concept of navigation through data using set of links. To access any piece of record, path is followed by navigating through linked dataset until the desired data is returned. Object database is the result of database functionalities combined with object oriented programming techniques. It is managed by object database management system (ODBMS) and has less usage in common data processes. In today's scenario, most commonly used database is of relational type.

Relational database contains basic data storing object called as table. Table is two-dimensional representation of data storage. It stores the data in the form of horizontal rows which in turn is divided into equal number of columns. Rows and columns are also referred as "tuples and "attributes" respectively. Actually the data is physically stored in data pages which are managed and allocated to a single table or group of tables by DBMS. Each data page starts with header information containing

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