Vague Criteria Relational Database Queries

Abstract

The most accessible interfaces querying relational database should allow vague terms included in selection criteria. The gradual property stands for the simplest vague selection criterion, but more categories of vague terms can be identified in a natural expression of a query. All of them can be modelled using fuzzy sets theory. A complete general syntax of a vague criterion of database selection will be concluded. Appropriate transformation or operations are defined in order to compute the degree of satisfaction for the vague criteria containing fuzzy terms.