A method and system for providing data integration of multiple data stores with diverse formats. The data integration engine accepts queries using a standard query language such as XML-QL, executes those queries against the multiple data stores, and returns the results. The data stores may include relational...http://www.google.es/patents/US7756904?utm_source=gb-gplus-sharePatente US7756904 - Nested conditional relations (NCR) model and algebra
Nested conditional relations (NCR) model and algebra
