A simple extension to the relational model that permits metadata (more generally metaknowledge) to be stored and manipulated as first class data is proposed. The accompanying query language is SQL extended with reification and reflection capabilities. Together, these extensions offer a relational framework for addressing a number of long-standing and modern database problems. Some rewriting properties of the query language are studied, and application to data integration along with a prototype implementation is described. Categories and Subject Descriptors H.2.1 [Database Management]: Logical Design—Data models; H.2.3 [Database Management]: Languages—Query languages General Terms Management, Languages, Design Keywords Metadata Management, Parameterized and Meta-Queries, Data Integration
Shun Yan Cheung, James J. Lu, Catharine M. Wyss