MSIS 635 DATABASE MANAGEMNT Database Systems Thomas Connolly

MSIS 635 DATABASE MANAGEMNT Database Systems Thomas Connolly and Carolyn Begg Third Edition – 2002 – ©Addison Wesley

PART I – BACKGROUND Chapter 1 - Introduction to Database Chapter 2 – Database Environment

Introduction – Some Database Applications n n n n Purchases from Supermarket Purchases using Credit Card Booking a holiday at the travel agents Using the local library Taking out Insurance Using the Internet Studying at the University

Introduction - Traditional File Based Systems n n A collection of application programs that perform services for the end-users such as the production of reports. Each program uses and manages its own data Limitations of file-based approach n n n Separation and isolation of data Duplication of data Data dependence Incompatible file formats Fixed Queries, proliferation of application programs

1. 3 Database Approach n n n Database – A shared collection of logically related data, and a description of the data, designed to meet the information needs of an organization. Centralized? (Vijay) – pp. 15 Database Management System (DBMS) – A software system that enables users to define, create, maintain and control access to the database. Views

Components of the DBMS n n Hardware Software Data Procedures n n n Log on Use a DBMS facility for application programs Start and stop the DBMS etc…

Roles in the Database Environment n n Data and Database Administrators Database Designers Application Developers Users

Advantages of DBMSs n n n n Control of data redundancy Data Consistency More Information from the same data Sharing of data Improved data Integrity Improved Security Enforcement of Standards

Advantages of DBMSs Contd n n n Economy of Scale Balance of Conflicting Requirements Increased Productivity Improved Maintenance through data independence Improved Concurrency Improved backup and Recovery of data

Disadvantages of DBMSs n n n Complexity Size Cost of DBMS Cost of Conversion Performance Higher Impact of failure