A foreign-key constraint (also called referential integrity constraint) on a column ensures that the value in that column is found in the primary key of another table.
Published in Chapter:
Merging, Repairing, and Querying Inconsistent Databases
Luciano Caroprese (University of Calabria, Italy) and Ester Zumpano (University of Calabria, Italy)
Copyright: © 2009
|Pages: 7
DOI: 10.4018/978-1-60566-242-8.ch039
Abstract
Data integration aims to provide a uniform integrated access to multiple heterogeneous information sources designed independently and having strictly related contents. However, the integrated view, constructed by integrating the information provided by the different data sources by means of a specified integration strategy could potentially contain inconsistent data; that is, it can violate some of the constraints defined on the data. In the presence of an inconsistent integrated database, in other words, a database that does not satisfy some integrity constraints, two possible solutions have been investigated in the literature (Agarwal, Keller, Wiederhold, & Saraswat, 1995; Bry, 1997; Calì, Calvanese, De Giacomo, & Lenzerini, 2002; Dung, 1996; Grant & Subrahmanian, 1995; S. Greco & Zumpano, 2000; Lin & Mendelzon, 1999): repairing the database or computing consistent answers over the inconsistent database. Intuitively, a repair of the database consists of deleting or inserting a minimal number of tuples so that the resulting database is consistent, whereas the computation of the consistent answer consists of selecting the set of certain tuples (i.e., those belonging to all repaired databases) and the set of uncertain tuples (i.e., those belonging to a proper subset of repaired databases).