Preference handling in relational query languages

The need for handling preferences in relational query languages arises naturally in real-world applications that deal with possible choices generated by the current state of the world captured in the relational data model. To address this problem, we propose a fully declarative language for encoding preferences conditional on the current state of the world represented as a relation database instance. Being based purely on the qualitative type of information about the preference model, the language supports encoding intuitive statements about preferences and having constructs for various kinds of preferences, the language leads to a flexible approach for specifying the most desirable choices of autonomous systems that act on behalf of their designers. Throughout the paper, we use an example of a control support system for a bank surveillance to motivate the need for our framework and to illustrate it.