COMM 226 Database Systems
INTRODUCTION A database is a structured collection of data, and is usually stored electronically to facilitate computerassisted search and retrieval. The electronic format allows different users to have views of the data that serve their particular needs. Furthermore, the database management software can ensure the consistency, integrity, and security of the database, provided the data needs of the organization have been correctly modeled and implemented. DATA MODELING Although the field of information systems engineering is young relative to most other engineering disciplines, it does apply formal modeling methods to study and predict aspects of a planned system. Different kinds of models may exhibit the user interfaces, behaviours, or data interchanges of the planned system. Modern businesses depend heavily on timely, trustworthy, and relevant data to provide a competitive advantage (Lau, 2010). As a result, organizations invest in modeling their enterprise data. Data models describe the logical and physical structure of data that the information systems maintain and process. The main goal of data modeling is to identify all of the data elements that the enterprise uses to manage its business, along with the structure and interrelationships of these elements. Data modeling typically follows activity modeling, which defines the functional requirements for the system. Its focus is to build a standard representation for the system’s data elements with little regard for when components of the system may create, modify, or access the data. This representation affords all applications a consistent, integrated view of the corporate information. The entity-relationship diagram (ERD) is the most commonly used model for designing databases. The ERD model identifies the important data elements and organizes them into a collection of entities and