Enhancing flexible querying using criterion trees

Abstract

Traditional query languages like SQL and OQL use a so-called WHERE clause to extract only those database records that fulfil a specified condition. Conditions can be simple or be composed of conditions that are connected through logical operators. Flexible querying approaches, among others, generalized this concept by allowing more flexible user preferences as well in the specification of the simple conditions (through the use of fuzzy sets), as in the specification of the logical aggregation (through the use of weights). In this paper, we study and propose a new technique to further enhance the use of weights by working with so-called criterion trees. Next to better facilities for specifying flexible queries, criterion trees also allow for a more general aggregation approach. In the paper we illustrate and discuss how LSP basic aggregation operators can be used in criterion trees. © 2013 Springer-Verlag Berlin Heidelberg.