A two-phased visual query interface for relational databases

Abstract

Developing an easy-to-use, visual query tool for non-expert users to perform their own ad-hoc queries from relational databases is an active research area. The challenge lies in designing a visual query application that is both versatile and user-friendly; often expressive power comes at the expense of non-intuitive user interfaces. This work is based on a novel two-phased approach, so that users first specify the subset of data that is of interest (using a so-called principal concept), whereby the query generates an intermediary dataset. In the second phase, users query this dataset to further eliminate unwanted rows through Boolean constraints and to perform any additional operations, i.e. grouping or columns renaming. The user interface has been kept simple and the presented ideas have been successfully implemented in a prototype known as OVI-2, for use with the university student database at Helsinki University of Technology. © Springer-Verlag Berlin Heidelberg 2007.