Students' Difficulties in Identifying the Use of Ternary Relationships in Data Modeling

Abstract

The present study examines the difficulties novice data modelers face when asked to provide a data model addressing a given problem. In order to map these difficulties and their causes, two short data modeling problems were given to 82 students who had completed an introductory course in database modeling. Both problems involve three entity sets with relationships between them, either ternary or binary. The students' solutions were classified according to the types of errors they committed. More than half of the students provided faulty solutions. After an analysis of these results, open interviews were conducted with a selected group of students in order to figure out the reasons underlying the students' erroneous decisions regarding the data model. Among the reasons for their erroneous solutions were insufficient experience, lack of reflection on their solution, and lack of immediate feedback. In addition, the authors suggest instructional modifications derived from the research results.

Untitled

“…Indeed, a key finding is that most of the students did not identify correctly the non-binary relationships. These results are in line with [14] that students encounter difficulties in identifying and modeling non-binary relationships.…”

“…In this research, we would like to reassure the findings in [14] concerning ternary relationships and explore more types of errors done by novice designers related to unary relationships, weak entities, and the hierarchy of entity-sets.…”

“…However, even when descriptions are clear, comprehensive and accurate, database design is still difficult. While novices find entities not difficult to model they face more difficulties with relationships [8], especially when ternary relationships are involved [8,14]. The difficulties in identifying the correct set of relationships among the entities specified lies in the potentially large number of possible relationships.…”

“…Yet another obstacle novice designer has to overcome is the identification of weak-entity-sets, containing entities that depend on other entities for their existence [14]. Identifying weak entities as regular ones would result in an erroneous solution, in which records of the weak type would not have a primary key to distinguish one from another.…”

“…The ternary relationship is perceived as a complex concept since it is more difficult to detect it, and due to its intricate multiplicity constraints. As a result, novice designers tend to avoid its use [14] although this does not always lead to the right solution that meets the requirements of the problem. From the excerpts of Ilan and Ron we may say that they did not perceive the fact that there is a loss of information derived from their binary-relationships based solution which can be attributed to a lack of multistructural level of understanding.…”