Vague Query Based on Vague Relational Model

Although the relational model for databases provides a great range of advantages over other data models, it lacks a comprehensive way to handle imprecise and uncertain data. Vague set, as a generalized fuzzy set, has more powerful ability to process fuzzy information than fuzzy set. In this paper, based on the vague set, a kind of vague relational model is proposed. Incorporating the notion of vague sets in relations, we describe Vague SQL, which is an extension of SQL for the vague relational model, and show that Vague SQL combines the capabilities of a standard SQL with the power of manipulating vague relations. Although Vague SQL is a minimal extension to illustrate its usages, VSQL allows users to formulate a wide range of queries between vague data and queries.