Database Reference
In-Depth Information
Chapter 8
An Extended Relational Model &
SQL for Fuzzy Multidatabases
Awadhesh Kumar Sharma
M.M.M. Engg College, India
A. Goswami
IIT Kharagpur, India
D.K. Gupta
IIT Kharagpur, India
ABSTRACT
This chapter investigates the problems in integration of fuzzy relational databases and extends the
relational data model to support fuzzy multidatabases of type-2 that contain integrated fuzzy relational
databases. The extended model is given the name fuzzy tuple source (FTS) relational data model which
is provided with a set of FTS relational operations to manipulate the global relations, called FTS rela-
tions, from such fuzzy multidatabases. The chapter proposes and implements a full set of FTS relational
algebraic operations capable of manipulating an extensive set of fuzzy relational multidatabases of
type-2 that include fuzzy data values in their instances. To facilitate formulation of global fuzzy query
over FTS relations in such fuzzy multidatabases, an appropriate extension to SQL can be done so as to
get fuzzy tuple source structured query language (FTS-SQL).
Many real world problems involve imprecise and ambiguous information rather than crisp information.
Recent trends in the database paradigm are to incorporate fuzzy sets to tackle imprecise and ambiguous
information of real world problems. Fuzzy query processing in multidatabases have been extensively
studied, however, the same has rarely been addressed for fuzzy multidatabases. This chapter attempts to
extend the SQL to formulate a global fuzzy query on a fuzzy multidatabase under FTS relational model
discussed earlier. The chapter provides architecture for distributed fuzzy query processing with a strategy
for fuzzy query decomposition and optimization. Proofs of consistent global fuzzy operations and some
of algebraic properties of FTS Relational Model are also supplemented.
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