↓見たいなの書いてんの？
@NamedNativeQuery(name="night&area", query="select night.id nid, night.night_duration, "
　　+ " night.night_date, area.id aid, night.area_id, area.name "
　　+ "from Night night, Area area where night.area_id = area.id", resultSetMapping="joinMapping")
@SqlResultSetMapping(name="joinMapping", entities={
　　@EntityResult(entityClass=org.hibernate.test.annotations.query.Night.class, fields = {
　　　　@FieldResult(name="id", column="nid"),
　　　　@FieldResult(name="duration", column="night_duration"),
　　　　@FieldResult(name="date", column="night_date"),
　　　　@FieldResult(name="area", column="area_id"),
　　　　discriminatorColumn="disc"
　　}),
　　@EntityResult(entityClass=org.hibernate.test.annotations.query.Area.class, fields = {
　　　　@FieldResult(name="id", column="aid"),
　　　　@FieldResult(name="name", column="name")
　　})
　　}
)