Modern Systems Analysis and Design

Chapter 12

Designing Databases

Chapter Objectives

Chapter 12 introduces students to database design, discussing both logical and physical database design. During logical design, logical data models are created for each known user interface, the logical models for each interface are integrated into a consolidated logical database model, the application’s conceptual E-R data model is translated into normalized data requirements, and the logical database model is then integrated with the translated E-R model. During physical design, decisions about data types, data structures, file organizations, and media are made.

This chapter introduces the relational data model, the most common notation used for representing detailed data requirements necessary for database design. Concepts of the relational data model, normalization principles for creating relational models with desirable properties, a process for combining different relational data models into a consolidated relational data model, and how to translate an entity-relationship data model into a relational data model are presented.

Chapter 12 reviews several choices systems builders have for the design of physical data storage structures. Chapter 12 emphasizes those decisions for which a systems analyst is most likely to have input, as opposed to the very technical data structure decisions made by database administrators and analysts. You should emphasize to your students throughout this section that physical design issues are addressed as part of a team of system analysts and technology specialists. Systems analysts bring an in-depth understanding of the application to the table, whereas technology specialists intimately understand the relative efficiency, security, integrity, and reliability of different technologies in different settings. To communicate with these specialists, systems analysts must have a sound knowledge of physical design issues, which is accomplished from studying the...