SISQL: schema-independent database querying (on and off the Web)

Finding information in diverse sources, in particular on the World-Wide Web is highly relevant these days. As more and more Web sites are administered by database systems, and as information on and off the Web increasingly comes out of a database, it is crucial to be able to search databases when working with the Web. This paper introduces a novel query language which renders it possible to formulate queries to databases in the absence of schema-knowledge. The proposed language Schema-Independent SQL (SISQL) takes parameterized SQL queries as input and dynamically generates correct SQL statements for collections of underlying schemata. SISQL is based on the Reflective Relational Algebra as a “processing engine,”, which has been proposed in recent years for overcoming the limitations of classical algebra w.r.t. the treatment of procedural data