Abstract
The work "Data Integration under Integrity Constraints'', published at the CAiSE~2002 Conference, proposes a rewriting technique for answering queries in data integration systems, when the global schema contains the classical key and foreign key constraints, and the mapping between the data sources and the global schema is of the global-as-view type. In this addendum, we explain why this research was important and how it gave raise to several results in the following years.