在项目中的数据库层中的数据库访问类都从DatabaseObject类派生，这样只需要在一个地方设置数据连接，其他地方都不需要涉及数据库访问的具体连接代码。

　　如：User类专门负责Users组的权限控制等，只需要简单的代码就可以连接并访问数据库了。这里具体实 现与此文章无关，只举一两个模块做例子。-In the project database layer of database access categories derived from DatabaseObject category, so only need to set up a local data connection, other places do not need to address the specific connectivity database access code. Such as: User categories Users Group responsible for access control, etc., only need a simple code you can connect and access the database of. Concrete realization of this has nothing to do with this article, to cite only one or two modules as an example.