Repairing and Querying Databases with Integrity Constraints

Data integration aims at providing a uniform integrated access to multiple heterogeneous information sources, which were designed independently for autonomous applications and whose contents are strictly related. There are several ways to integrate databases or possibly distributed information sources, but whatever integration architecture we choose, the heterogeneity of the sources to be integrated causes subtle problems. In particular, the database obtained from the integration process may be inconsistent with respect to integrity constraints; that is, one or more integrity constraints are not satisfied. The following example shows a case of inconsistency.