Integration of relational databases in a multidatabase system based on schema enrichment

The authors describe a framework for an object-oriented modeling of meta information and its use for the integration of heterogeneous databases with the goal of their interoperation. The meta information consists of all types of information necessary to access and interoperate the participating databases. As part of the meta information, they model the common properties and differences of the various data models and concrete systems. Additionally, they also include information to semantically enhance the schemas of the participating databases providing the basis for a (semi-)automatic schema transformation. They describe the semantic richment of a relational schema using additional information deduced from its underlying entity-relationship design schema. The enhanced relational schemas may be automatically transformed into corresponding schemas in the common data model which in this case is the object-oriented model. Queries using the created object-oriented schema may be automatically translated into equivalent SQL queries for the original relational schema