Foundations of Query Answering on Inconsistent Databases

Abstract

Notwithstanding the traditional view that database instances must respect all integrity constraints imposed on them, it is relevant to develop theories about how to handle database instances that violate some integrity constraints, and more particularly, how to cope with query answering in the presence of inconsistency. Such a theory developed over the past twenty years is currently known as consistent query answering (CQA). The aim of this article is to summarize and discuss some core concepts and theoretical developments in CQA.