NUL: a Navigational User's Language for a network structured data base

ABSTRACT

This paper presents an end-user's language which tries to solve the problem of an easy navigation through a DBTG-like data base structure. A request is expressed in a nonprocedural and hierarchically structured fashion. The dialogue is split into two main parts : first a data context definition, then the manipulations of this context.A context is a part of the data base that the user is concerned with. A context definition is formed by a set of labelled lines; each line is a condition declaration on one entity-set. By means of labels and link names declared in the data structure, a line may be connected to another one; this expresses a 'join', by the named link, between the two entity-sets involved in the two lines.The originality of the language lies in the fact that it permits the user to navigate easily and fairly naturally from one entity-set to another through a link; in fact, this navigation is mapped into a hierarchical structure which appears more comprehensible to the user.On the other hand, a manipulation is a command such as print, update, insert or other standard actions the user may want to execute on the context.

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INDEX TERMS

Keywords:
casual user, data base management systems, data manipulation language, entity-relationship model, navigation, network model, query language