An Extension of Data Description Language (DDL) for Fuzzy Data Handling
Ignacio José Blanco, Nicolás Marı́n, Olga Pons, M.A. Vila · Flexible Query Answering Systems · 2001
In this paper, we extend an existing relational language such as SQL with capabilities for representing and handling imprecise information. We add new sentences to manage new types based on a domain concept extension. New values for these types are added, including three ones for a more specialized management of NULL values.