A Knowledge-Based Approach for Answering Fuzzy Queries over Relational Databases

摘要

Users often have vague or imprecise ideas when searching the database. Thus, they might like to issue fuzzy queries for possibly retrieving. Based on fuzzy sets theory and the knowledge base related to the application domain, this paper proposes an approach translating the fuzzy query into the precise query and extending the query criteria ranges in order to provide approximate answers to the user. The fuzzy condition is first defined by a fuzzy number with membership function, and then is translated into the precise condition by using the a-cut operation of fuzzy number. The tuples satisfying the fuzzy query are finally ranked according to their satisfaction degree.