Database Design Using the REA Data Model Chapter

Learning Objectives • Discuss the steps for designing and implementing a database system. • Use the REA data model to design an AIS database. • Draw an REA diagram of an AIS database. • Read an REA diagram and explain what it reveals about the business activities and policies of the organization being modeled. Copyright © 2015 Pearson Education, Inc. 17 -2

Database Design Process Copyright © 2015 Pearson Education, Inc. 17 -3

Data Modeling • Process of defining a database so that it faithfully represents all aspects of the organization, including its interactions with the external environment. ▫ Entity-relationship (E-R) diagrams ▫ REA data model Copyright © 2015 Pearson Education, Inc. 17 -4

REA Modeling • Resources ▫ Things that have economic value to the organization (e. g. , inventory, cash) • Events ▫ Various business activities that management wants to collect information on • Agents ▫ People and organizations that participate in events (both internal (e. g. , employees) and external (e. g. , customers/vendors) to the organization) Copyright © 2015 Pearson Education, Inc. 17 -5

REA Basic Template Copyright © 2015 Pearson Education, Inc. 17 -6

Creating an REA Model • Identify relevant events ▫ Give-get exchange (economic duality) • Identify resources and agents ▫ Resource reduced in give event ▫ Resource acquired in get event • Determine cardinalities of relationships ▫ Nature of the relationship between the two entities Copyright © 2015 Pearson Education, Inc. 17 -7

Cardinality Notation Methods • Graphical symbols ▫ Graphical symbols represent minimum–maximum cardinalities • (Min, Max) notation ▫ Pairs representing the minimum–maximum cardinalities • UML notation ▫ Pairs representing the minimum–maximum cardinalities • Maximums only (Microsoft Access) Copyright © 2015 Pearson Education, Inc. 17 -8

Key Terms • Data modeling • Entity-relationship (E-R) diagram • REA data model • Resources • Events • Agents • Cardinalities Copyright © 2015 Pearson Education, Inc. • • Minimum cardinality Maximum cardinality One-to-One (1: 1) relationship One-to-Many (1: N) relationship • Many-Many (M: N) relationship 17 -9