How can Oracle interoperate with a non-Oracle database?
Oracle provides two connectivity solutions to address the needs of disparate data access: Oracle Transparent Gateways and Oracle Generic Connectivity. Oracle Transparent Gateways provides access to many non-Oracle data stores, including Microsoft SQL Server, Informix, Ingres, and Sybase from an Oracle environment. Oracle Generic Connectivity provides access to many data stores for which Oracle does not have a gateway solution. This feature enables transparent connectivity using ODBC and OLE DB.