An extended database design methodology for uncertain data management

Many real world systems require the support of database management systems (DBMS) that can handle vague or imprecise data. Fuzzy theory has been shown to be particularly suitable for this purpose. Indeed there have been sever al proposals for extending the relational data model in order to represent and query fuzzy data. However, little work has been done in modeling uncert ainty at the conceptual schema level or for mapping such a schema to a rela tional DBMS. To fill this gap, we propose fuzzy entity-relationship methodo logy (FERM), which is a comprehensive methodology for design and developmen t of fuzzy relational databases. FERM includes an extended fuzzy entity-rel ationship model to capture imprecision at the schema level as well as gener ic rules for mapping this schema to relational databases-In this paper, we also show the application of FERM to build a prototype of a fuzzy database for a discrete control system for a semiconductor manufacturing process. (C ) 1999 Elsevier Science Inc. All rights reserved.