1. A computer-implemented method in a data processing system for providing a single set of object relational mappings for a set of objects across different instances of same schemas, comprising: configuring multiple datasources for a class; setting a mapping identifier at runtime, wherein the mapping identifier is used by a computer to access a particular datasource of the multiple datasources; generating mapping code from the particular datasource based on the mapping identifier; acquiring a schema identifier from the generated mapping code; prepending the schema identifier to tables in a SQL generated code; and using a schema name associated with the schema identifier to connect to a schema instance in the particular datasource for accessing the particular datasource by the computer.