In this paper, the interest of fuzzy sets and possibility theory in the context of databases is presented. It is shown that these " notions provide an homogeneous framework for both the representation of imprecise/uncertain information and vague queries. A special emphasis is put on flexible queries addressed to regular databases. When comparing various attempts made in this contexL the fuzzy set approach turns out to generalize the other solutions. Finally, the principal features of a fuzzy querying language extending SQL are outlined.