A method, system, and computer instructions for providing a single set of object relational mappings across different instances of the same schemas. With the present invention, multiple datasources are first configured for class (or set of object definitions). A mapping identifier is set at runtime, wherein the mapping ID is used to access the correct datasource. Mapping code is then generated from the datasource based on the mapping identifier. A schema identifier is acquired from the generated mapping code and prepended to tables in the in the SQL generated code. The schema name is used to connect to the correct schema within a datasource. The mapping ID is also used to access the correct JNDI name to access the correct data source which represents a physical database.