Database and Characteristic of Database

Database and Characteristic of Database 

A database is collection of related data.Data means known facts that can be recorded and that have implicit meaning. A database may be generated and maintained manually or it may be computerized.A library card catalog is a database may be created and maintained manually.A computerized database may be created and maintained by a group of application programs written specially for that take or by a database management system.

A database management system is a collection of programs that enables users to create and maintain a database.The DBMS is a general purpose software system.The database definition or descriptive information is also stored by the DBMS in the form of a database catalog.It is called meta-data.

Database and database technology have a major impact on the growing use of computers.Database play a critical role in almost all areas where computers are used including business,electronic,education,library science etc.

An example of a large commercial database is Amazon.com.The database occupies over 2 terabytes and is stored on 200 different computers called server.     

Characteristic of Database Approach

A number of characteristic distinguish the database approach from the much older approach of programming with files.

In database approach single repository maintains data that is defined once and then accessed by various users.In database the names and labels of data are defined once and used repeatedly by queries.

Main characteristic of database system is

• Self describing nature of a database system.
• Support multiple view of data.
• Sharing of data and multi-user transaction processing.
• Insulation between programs and data and data abstraction.

Self Describing nature of a database system

The database system contains not only the database itself but also a complete definition of database structure and constraints.This definition is stored in the DBMS catalog which contains information such as structure of each file,the type and storage format of each item.This information stored in the catalog is called meta-data.

Support of multiple views of the data

A database has many users each of whom may requires a different view of the database.A view may be a subset of the database or it may contain virtual data that is derived from the database.

Sharing of data and multi-user transaction processing

Database allow multiple users to access the database at the same time.If data for multiple application is to be integrated and maintained in a single database.The DBMS must include concurrency control software to ensure that several users trying to update the same data to do in a controlled manner so that the result of the updates is correct.`

Insulation between programs and data and data abstraction

The structure of data files is stored in the Database management system catalog separately from the access programs.This property is called program-data independence.

The characteristic that allows program data independence and program operation independence is called data abstraction.A DBMS provides users with a conceptual representation of data that does not include many of the details of how the data is stored or how the operations are implemented.The data model hide storage and implementation details that are not in interest of most database users.