A fuzzy query language for relational databases

A fuzzy query language (FQL) for relational databases is proposed. FQL, constructed as an enhancement of the relational domain calculus, has sufficient capability to represent all four types of the fuzzy statements distinguished by the work of L.A. Zadeh (1978). The idea for constructing FQL is in the formulation of the fuzzy matching degrees that assigns the appropriate values in the interval to any combination of fuzzy queries and tuples in relational databases. FQL helps to provide a human-oriented interface to relational databases that store a vast amount of information. Furthermore, fuzzy expert systems are expected to be provided with the facility to make use of fact data in relational databases through FQL. In addition, FQL is a theoretical basis for systematically developing a higher human-oriented interface with relational databases