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The notion of a database query is generalized for databases with user-defined functions. Then, we can prove that the computable queries coincide with those expressible by an extension of the relational machine, with oracles (). This implies that any complete query language, extended with user-defined function symbols in a "reasonable" way, is still complete. We give an example of a complete query language with user-defined functions, and discuss its connections with object inventions.
Dan Suciu, "Queries on Databases With User-Defined Functions", . June 1993.
Date Posted: 17 July 2007