Embodiments are provided to define relationships for merging template or database part tables with one or more database tables in a computer system. A database application may utilize a schema to receive metadata associated with a target database part table in one or more markup language elements. The database application may then receive metadata associated with a source database table to be joined with the target table in the schema elements. The database application may then receive join type metadata in the schema elements. The join type metadata may specify whether fields from the source table are to be merged into the target table or whether fields from the target table are to be merged into the source table. In response to receiving the target table metadata and the source table metadata, the database application may then merge the target and source tables utilizing the join type metadata.