1 - Introduction

Abstract

This chapter reviews the basic concepts of database management and introduce the role of data modeling and database design in the database life cycle. The basic component of a file in a file system is a data item, which is the smallest named unit of data that has meaning in the real world. A group of related data items treated as a unit by an application is called a record. Examples of types of records are order, salesperson, customer, product, and department. A file is a collection of records of a single type. Database systems have built upon and expanded these definitions: In a relational database, a data item is called a column or attribute, a record is called a row or tuple, and a file is called a table. A database is a more complex object; it is a collection of interrelated stored data that serves the needs of multiple users within one or more organizations—that is, an interrelated collection of many different types of tables. A database management system (DBMS) is a generalized software system for manipulating databases. A DBMS supports a logical view (schema, subschema); physical view (access methods, data clustering); data definition language; data manipulation language; and important utilities such as transaction management and concurrency control, data integrity, crash recovery, and security. Among the variety of data modeling approaches, the entity-relationship (ER) and Unified Modeling Language (UML) data models are arguably the most popular in use today because of their simplicity and readability. Knowledge of data modeling and database design techniques is important for database practitioners and application developers.