2 - Database modeling

Abstract

A database is a set of facts about an application domain. An application domain is also known as Universe of Discourse (a term coined by the 19th century mathematician Augustus De Morgan). The content of an application domain can be viewed at four different levels: conceptual, logical, physical, and external. The external level deals with the user interface; it is about designing the information that is going to be presented to various user groups. At the conceptual level, the information is specified naturally using language and concepts that can be understood by nontechnical domain experts. At this high level of communication, object-role modeling (ORM) provides the best approach. Logical level specifies the information in terms of data structures supported by a logical data model. Physical level is used to choose a target database management system (DBMS) for implementing the logical model. The database life cycle is a core component of the information systems life cycle. The purpose of the database life cycle is to define database requirements and manage database solutions to support the information system life cycle objectives. Tasks include managing data, and selecting and managing database products such as database server hardware and relational database management system (RDBMS) software. Visio for enterprise architect's (VEA) database modeling functions can help both individual database users and large corporate development teams. Individual database users do their own business analysis and database modeling.