NQS — a graphical query system for data models with binary relationship types

Abstract

A graphical query system for data models with binary relationship types is described in which queries can be formulated as annotated graphs. The concepts of the underlying descriptive query language allow to represent even complex queries in a graphical form that is easy to understand. Identifiers with local scope and the possibility to build queries in a step by step manner help to avoid problems sometimes mentioned in connection with the formulation of complex queries in descriptive query languages. Query formulation is supported by comfortable operations on graphs and by an efficient layout algorithm.