Data structure diagram

Abstract: While implementation/logical data models have been extensively studied and reported on, there is relatively less attention on the conceptual data models, especially from an end-user empirical perspective. Conceptual models are more suited for end-users due to the richness in semantic expressiveness and user-oriented features, but usually are not directly implemented. In this article, we examine three conceptual models: data structure diagram, entity-relationship model, and object-oriented model from the viewpoint of endusers. Results of two empirical studies, one experimental and one survey, are described. A comparative examination of the three data models on comprehension, efficiency, productivity, and a whole host of other characteristics has been made. The general evidence from the experimental study is that the user performance is much superior in terms of comprehension, efficiency, and productivity using the object-oriented model than the data structure diagram or the entity-relationship model. The second study suggests that this clear user preference for the OOM model diminishes with increased computer and database experience. Given the explosive growth in recent years of end-user computing and their use of databases, the findings of this study should be of great concern for users as well as information systems specialists.

Abstract: Data base management systems have grown rapidly in their power and complexity over the 15-year history of data processing on commercially available computers. The original concepts have split, and new terms have been adopted to name and refer to these concepts. The Data Structure Diagram graphic technique is used to illustrate the splitting of the concepts and the structural relations which exist between these concepts at each point in the evolution.

Abstract: A data structure for a particular application, for example the enrolment record of a college, is entered into a machine by plotting an appropriate structure diagram 1 on a display of the machine using an appropriate keyboard. The structure diagram 1 comprises labels within boxes 2 denoting the types of data entry which it is intended to index, and links 4 joining the boxes 2 and denoting the relationships between the different types of data entry. When the design of the data structure diagram 1 has been completed the form in which the indexed data is to be displayed on entry and retrieval is determined by designing one or more dummy forms. When data is subsequently entered into the machine and retrieved using the forms, the data is automatically indexed and the indexed data is selectively displayed in dependence on the previously design data structure diagram 1. Furthermore it is a straightforward matter to modify the manner in which the data is indexed by the machine by changing the data structure diagram 1.