Relational Databases and Fuzzy Sets Background

In this chapter we will provide an overview of relational databases and fuzzy set theory as will be needed when we describe the various fuzzy relational extensions in following chapters. The relational model has been highly influential based both on its sound mathematical foundations and highly successful implementations. First the formal definition of the relational model will be presented and then the design process will be discussed in more detail. In chapter 1 we have seen how entity-relationship modeling led to a relational data base design. Also we will describe the design approach using functional dependencies to develop the relations of the database and then briefly describe the querying of relational models by relational algebra, relational calculus and the higher level SQL language.