Data integration systems provide a uniform query interface (UQI) to multiple, autonomous data sources [4]. This paper presents the universal data model (UDM) that captures the semantically salient aspects of relational, entity-relationship, and XML data models. As a consequence, UDM -- including its accompanying query language -- provides a simple and elegant UQI for integrating data represented in some of the most widely adopted data models. Key words: Data Model, Data Integration, Query Languages
James J. Lu