Relative Qualification in Database Flexible Queries

The simplest vague selection criterion in database queries is often expressed by a gradual property, or in other words, a certain qualification required to the targeted objects. Complex criteria often combine two or more simple and independent criteria, through an aggregation operation that means a multi-qualification of the searched objects. But there are also cases when in a complex criterion, one of the qualification is applicable in the context created from another attribute values, that means relative qualification. The relative qualification to another gradual property and the relative qualification to another crisp attribute are presented in the paper. In order to complete a real database querying problem, adequate procedures to dynamical defining linguistic values on database attributes are also proposed