Teaching Database Modeling and Design: Areas of Confusion and Helpful Hints

Abstract

Executive SummaryThis paper identifies several areas of database modeling and design that have been problematic for students and even are likely to confuse faculty. Major contributing factors are the lack of clarity and inaccuracies that persist in the presentation of some basic database concepts in textbooks. The paper analyzes the problems and discusses ways to minimize them. Specifically, the paper discusses the practical role of normalization in database design, addresses the confusion in representing attributes with repeating values, discusses how to remove inconsistencies in defining relations and first normal form, simplifies the process of identifying candidate keys to normalize relations, clarifies the conditions under which insertion and deletion anomalies may occur, and sheds light on the confusion in defining weak entities.Normalization plays a vital role in both the theory and the practice of database design. The topdown approach popularly used in relational database design creates a conceptual schema that is represented by entity-relationship (E-R) models, and then uses mapping rules to convert the conceptual schema to relation schemas. Because E-R modeling is an intuitive process, errors could occur in identifying entities and their relationships, resulting in un-normalized relations. Unnormalized relations also could result from converting files in legacy systems and spreadsheets to relational tables. Normalization plays a key role in verifying the goodness of design of such relations and in improving the design.The concept of repeating values in relations plays a major role in defining relations and first normal form. Yet, textbooks in general do not distinguish between multi-valued and single-valued attributes in a schema. This lack of clarity may result in conflicting interpretations of the schema. The paper presents a simple solution to the problem.The lack of clarity in defining the terms tables, relations, and first normal form (1NF) in textbooks is another potential source of confusion. Some books define relation as a A challenging task for many students during the normalization process is checking whether a determinant is a Material published as part of this publication, either on-line or in print, is copyrighted by the Informing Science Institute. Permission to make digital or paper copy of part or all of these works for personal or classroom use is granted without fee provided that the copies are not made or distributed for profit or commercial advantage AND that copies 1) bear this notice in full and 2) give the full citation on the first page. It is permissible to abstract these works so long as credit is given. To copy in all other cases or to republish or to post on a server or to redistribute to lists requires specific permission and payment of a fee. Contact Publisher@InformingScience.org to request redistribution permission.Teaching Database Modeling and Design 482 candidate key. The standard method is to check whether every attribute of the relation is functionally dependent on ...

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