Introduction to Databases CHAPTER 1 Introduction to Databases DDC 2483 DATABASE

1.1 Introduction Basic terms: Database – A collection of related data Database Management System (DBMS) – The software that manages and controls access to the database Database Application – A program that interacts with the database at some point in its execution Database System – A collection of application programs that interact with the database along with the DBMS and the database itself DDC 2483 DATABASE

1.1 Introduction Examples of Database Systems Purchases from the supermarket Purchases using your credit card Booking a holiday at the travel agents Using the local library Renting a video Using the Internet DDC 2483 DATABASE

1.1 Traditional File-Based Systems It is the predecessor for database system The good reasons for studying it: Understanding the problems inherent in file- based systems may prevent us from repeating these problems in database system If you wish to convert a file-based system to a database system, understanding how the file system works will be extremely useful DDC 2483 DATABASE

1.2 File Based Approach and Limitations of the File-based Approach File-based system – A collection of application programs that perform services for the end-users, such as the production of reports. Each program defines and manages its own data. DDC 2483 DATABASE

1.2 File Based Approach and Limitations of the File-based Approach Separation and isolation of data Duplication of data Data dependence Incompatible file formats Fixed queries/proliferation of application programs DDC 2483 DATABASE

1.3 Database Approach and The Database Management System (DBMS) Database – Shared collection of logically related data (and a description of this data), designed to meet the information needs of an organization. DDC 2483 DATABASE

1.3 Database Approach and The Database Management System (DBMS) Shared collection – can be used simultaneously by many departments and users. Logically related - comprises the important objects and the relationships between these objects. Description of the data – the system catalog (meta-data) provides description of data to enable data independence. DDC 2483 DATABASE

1.3 Database Approach and The Database Management System (DBMS) Database Management System (DBMS) – A software system that enables users to define, create, and maintain the database and that provides controlled access to this database. DDC 2483 DATABASE

1.3 Database Approach and The Database Management System (DBMS) DDC 2483 DATABASE

1.4 Components of the DBMS environment Hardware Can range from a PC to a network of computers. Software DBMS, operating system, network software (if necessary) and also the application programs. Data Used by the organization and a description of this data called the schema. DDC 2483 DATABASE

1.4 Components of the DBMS environment Procedures The instructions and rules that govern the design and use of the database. People The people that involved with the system DDC 2483 DATABASE

1.5 Roles in the Database Environment Data and Database Administrator Database Designers Application Developers End-Users DDC 2483 DATABASE

1.6 Advantages and Disadvantages of DBMS Control of data redundancy Data consistency Sharing of data Improved data integrity Improved maintenance through data independence. DDC 2483 DATABASE

1.6 Advantages and Disadvantages of DBMS Complexity Cost of DBMS Cost of conversion Performance Higher impact of a failure DDC 2483 DATABASE