Enhancing the Semantics of Federated Schemata by Translating SQL-Queries intoObject Methods

摘要

The paper argues the feasibility of equipping object-oriented federated schematawith methods reflecting operations on the component schemata extracted from the applications. An algorithm to obtain object methods in an object-oriented DML from SQL-queries is described, based on the matching of query join graphs with object structures. It is shown that the navigational structure provided by the object model can be exploited to present joins and nesting constructs contained in an SQL-query. It is also shown that with such a translation, considerable gain in the intuitive meaning of the query can be achieved. When applied to queries from applications on the underlying data bases in a federated data base system, both the subsequent schema integration phase and the development on new, federated, applications benefit from this additional insight in the semantics of the underlying schema.