多个数据库模式可用来围绕长期数据库对话所固有的矛盾形势而工作，因为每一个用户可从共用数据库拷贝数据这不同于他／她的专用数据库，该数据库与共用数据库至少在表面上分开，这样用户就能避免矛盾形势。-organization of data on secondary storage. The importance of this aspect, particularly for the personal computer user, is that this greatly simplifies database usage. The user can store, access and manipulate data at a high level (close to the application) and be totally shielded from the low level (close to the machine) details of data organization. We will not discuss details of specific PC DBMS software packages here