Object-relation mapping(ORM) handles persisting objects to and from the records of underlying relation database, it is an object-oriented method to develop application.
对象-关系映射就是把对象映射到关系数据库中的记录，它是完全从面向对象的角度来设计和开发程序的。
2
It is an important research content of GIS fields in the recent years to store and manage mass GIS basic graphics data and attribute data using object-relation database.
The natural properties and human culture properties of the origin as well as the subject - objectrelation between instruments and human are also discussed.