Introduction to DatabaseSystems
An organization must have accurate and reliable data (information) for effective decision making. Data (information) is the backbone and most critical resource of an organization that enables managers and organizations to gain a competitive edge. In this age of information explosion, where people are bombarded with data, getting the right information, in the right amount, at the right time is not an easy task. So, only those organizations will survive that successfully manage information. A databasesystem simplifies the tasks of managing the data and extracting useful information in a timely fashion. A databasesystem is an integrated collection of related files, along with the details of the interpretation of the data. A Data Base ManagementSystem is a software system or program that allows access to data contained in a database. The objective of the DBMS is to provide a convenient and effective method of defining, storing, and retrieving the information stored in the database. The database and databasemanagementsystems have become essential for managing business, governments, schools, universities, banks etc.
1.2 BASIC DEFINITIONS AND CONCEPTS
In an organization, the data is the most basic resource. To run the organization efficiently, the proper organization and management of data is essential. The formal definition of the major terms used in databases and databasesystems is defined in this section. 1.2.1 Data
The term data may be defined as known facts that could be recorded and stored on Computer Media. It is also defined as raw facts from which the required information is produced. 1.2.2 Information
Data and information are closely related and are often used interchangeably. Information is nothing but refined data. In other way, we can say, information is processed, organized or summarized data. According to Burch et. al., "Information is data that have been put into a meaningful and useful content and communicated to a recipient who uses it to made decisions". Information consists of data, images, text, documents and voice, but always in a meaningful content. So we can say, that information is something more than mere data. Data are processed to create information. The recipient receives the information and then makes a decision and takes an action, which may triggers other actions.
In these days, there is no lack of data, but there is lack of quality information. The quality information means information that is accurate, timely and relevant, which are the three major key attributes of information. 1. Accuracy: It means that the information is free from errors, and it clearly and accurately reflects the meaning of data on which it is based. It also means it is free from bias and conveys an accurate picture to the recipient. 2. Timeliness: It means that the recipients receive the information when they need it and within the required time frame. 3. Relevancy: It means the usefulness of the piece of information for the corresponding persons. It is a very subjective matter. Some information that is relevant for one person might not be relevant for another and vice versa e.g., the price of printer is irrelevant for a person who wants to purchase computer. So, organization that have good information system, which produce information that is accurate, timely and relevant will survive and those that do not realize the importance of information will soon be out of business. 1.2.3 Meta Data
A meta data is the data about the data. The meta data describe objects in the database and makes easier for those objects to be accessed or manipulated. The meta data describes the database structure, sizes of data types, constraints, applications, autorisation etc., that are used as an integral tool for information resource management. There are three main types of meta data: 1. Descriptive meta data: It describes a resource for purpose such as discovery and...
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