Database systems

A database-management system is a collection of interrelated data and a set of programs to access those data. The collection of data, usually referred to as the database, contains information relevant to an enterprise. The primary goal of a DBMS is to provide a way to store and retrieve database information that is both convenient and efficient.

Database systems are designed to manage large bodies of information. Management of data involves both defining structures for storage of information and providing mechanisms for the manipulation of information. In addition, the database system must endure the safety of the information stored, despite system crashes or attempts at unauthorized access. If data are to be shared among several users, the system must avoid possible anomalous results.

Because information is so important in most organizations, computer scientists have developed a large body of concepts and techniques for managing data.

DATA BASE-SYSTEM APPLICATIONS

Databases are widely used. Here are some representative applications

Banking: For customer information, accounts, loans, and banking transactions.

Airlines: For reservations and schedule information. Airlines were among the first to use database in a geographically distributed manner.

Universities: For student information, course registrations, and grades.

Credit card transactions: For purchases on credit and generation of monthly statements.

Telecommunication: For keeping records of calls made, generating monthly bills, maintaining balances on prepaid calling cards, and storing information about the communication networks.

Sales: For customer, product, and purchase information.

On-line retailers: For sales data noted above plus on-line order tracking, generation of recommendation lists, and maintenance of on-line product evaluations.

Manufacturing: For management of the supply chain and for tracking production of items in factories, inventories of items in warehouse and stores, and orders for items.

Human resources: For information about employees, salaries, payroll taxes, benefits, and for generation of paychecks

PURPOSE OF DATABASE SYSTEMS

Database systems arose in response to early methods of computerized management of commercial data. As an example of such methods, typical of the 1960s consider part of a bank enterprise that, among other data, keeps information about all customers and savings accounts. One way to keep the information on a computer is to store it in operating system files. To allow users to manipulate the information, the system has a number of application programs that manipulates the file, including programs to

· Debit or credit an account
· Add a new account
· Find the balance of an accountGenerate monthly statements