A study of fuzzy query systems for relational databases

Author(s):  
Rachid Mama ◽  
Mustapha Machkour
2021 ◽  
pp. 1-12
Author(s):  
Rachid Mama ◽  
Mustapha Machkour

 Nowadays several works have been proposed that allow users to perform fuzzy queries on relational databases. But most of these systems based on an additional software layer to translate a fuzzy query and a supplementary layer of a classic database management system (DBMS) to evaluate fuzzy predicates, which induces an important overhead. They are not also easy to implement by a non-expert user. Here we have proposed a simple and intelligent approach to extend the SQL language to allow us to write flexible conditions in our queries without the need for translation. The main idea is to use a view to manipulate the satisfaction degrees related to user-defined fuzzy predicates, instead of calculating them at runtime employing user functions embedded in the query. Consequently, the response time of executing a fuzzy query statement will be reduced. This approach allows us to easily integrate most fuzzy request characters such as fuzzy modifiers, fuzzy quantifiers, fuzzy joins, etc. Moreover, we present a user-friendly interface to make it easy to use fuzzy linguistic values in all clauses of a select statement. The main contribution of this paper is to accelerate the execution of fuzzy query statements.


Author(s):  
Rachid Mama ◽  
Mustapha Machkour ◽  
Mourad Ennaji ◽  
Karam Ahkouk

Author(s):  
Jóse Galindo ◽  
Angélica Urrutia ◽  
Mario Piattini

Some approaches about fuzzy ER/EER model have been published recently. Few of these works study how to relax constraints and other aspects expressed in the model. In this chapter our aim is to relax some semantic aspects which have not been studied in previous works and to extend the EER model with fuzzy capabilities. We use fuzzy quantifiers and fuzzy degrees which have been widely studied in the context of fuzzy sets and fuzzy query systems for databases. We will also examine the representation of these new features in an EER model and their practical repercussions. The studied extensions are: fuzzy aggregations and fuzzy aspects on specializations, such as fuzzy degrees, fuzzy completeness constraint, fuzzy cardinality constraint on overlapping specializations, fuzzy disjointed or overlapping constraints, fuzzy attribute defined specializations, fuzzy constraints in union types or categories and fuzzy constraints in shared subclasses (or intersection types). All these fuzzy extensions have a new meaning and offer greater expressiveness in conceptual design.


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