Queries to a database can be made more powerful and user friendly by referring to, cases, either for expressing the request, or for computing,the answer. This requires some similarity-based reasoning facilities. In this paper, we present an implemented information system (applied to a database describing houses to be rent), based on an approach developed in the fuzzy set and possibility theory setting. This provides an unified framework for expressing user's preferences about what he is looking for, for weighting the importance of requirements, for expressing similarity relations, for referring to examples that he likes and/or counter-examples that he dislikes, and for maidng case-based predctions.