Lesson 1 (Database Management System).pptx

# DATABASE MANAGEMENT SYSTEM ## OBJECTIVES - Distinguish between data and information and Knowledge - Describe basic concepts of ER Model - Describe components of a data model - Describe basic constructs of E-R Modeling - Describe data modeling as a part of database design process - Describe steps i...

# DATABASE MANAGEMENT SYSTEM ## OBJECTIVES - Distinguish between data and information and Knowledge - Describe basic concepts of ER Model - Describe components of a data model - Describe basic constructs of E-R Modeling - Describe data modeling as a part of database design process - Describe steps in building the data model - Describe developing the basic schema # INTRODUCTION A database-management system (DBMS) is a collection of interrelated data and a set of programs to access those data. This is a collection of related data with an implicit meaning and hence is a database. 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. By data, we mean known facts that can be recorded and that have implicit meaning. For example, consider the **names**, **telephone numbers**, and **addresses** of the people you know. You may have recorded this data in an indexed address book, or you may have stored it on a diskette, using a personal computer and software such as DBASE IV or V, Microsoft ACCESS, or EXCEL. A **datum** - a unit of data - is a symbol or a set of symbols which is used to represent something. This relationship between symbols and what they represent is the essence of what we mean by **information**. Hence, information is interpreted data - data supplied with semantics. **Knowledge** refers to the practical use of information. While information can be transported, stored or shared without many difficulties the same cannot be said about knowledge. Knowledge necessarily involves a personal experience. Referring back to the scientific experiment, a third person reading the results will have information about it, while the person who conducted the experiment personally will have knowledge about it. 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 ensure 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. These concepts and technique form the focus of this book. This chapter briefly introduces the principles of database systems.