The approaches above, however, are targeted towards the integration of heterogeneous relational databases into a multidatabase.
Mediators resolve conflicts so that data from multiple information sources can be integrated.
Other problems that are studied are aggregation and composition conflicts. The language or model provide constructs to resolve conflicts among the sources. Conf. on Data Engineering, Tempe, AZ, February 1992. Although they research many issues in query processing, this work cannot be applied in the context of heterogeneous DBMS, supporting SQL like query languages. The language or model provide constructs to resolve conflicts among the sources.