Towards a Flexible Relational Database Query System

In many cases information is found to be naturally fuzzy or imprecise, that's why flexible query systems have become indispensable to represent and manage this information and especially facilitate interrogation to a non-expert user, the problem is that Boolean queries do not allow the user to use vague and imprecise language terms in the qualification criteria of the searched data or to express preferences between these criteria. Nowadays, there are many proposals that allow users to make flexible queries on relational databases. In this paper, we will briefly review the main attempts to find a perfect solution to this problem, highlighting their advantages, disadvantages and difficulties encountered. Finally, as a result of this comparative study, we present an intended model of the flexible relational database query system.