关系型数据库的数据依赖及应用程序设计

数据依赖是关系型数据库数据之间的内在联系，在数据库规范化设计中数据依赖起着重要的作用。数据依赖的主要类型是函数依赖，函数依赖分为完全函数依赖、部分函数依赖和传递函数依赖。在实际应用中数据依赖又包括简单函数依赖和复杂函数依赖、内部依赖关系和外部依赖关系。为阐明这些数据依赖关系的概念和应用，引入一个“物业收费管理系统”的实例，介绍关系型数据库中数据依赖在实际应用中的设计方法，以及内部依赖关系和外部依赖关系在该应用实例中的程序设计过程。

Design of Data Dependencies in Relation Database and Application Development

Data dependencies is a kind of internal relation between data in relation database, it acts an important role in standardization design of database. The main type of data dependencies is functional dependencies, functional dependencies includes full data dependencies, partial data dependencies and transferring data dependencies. In practical application, data dependencies includes simple dependencies and complicated dependencies, internal dependencies and external dependencies. In order to illustrate the concept and the application about these data dependencies, an example about management system used in house charging is quoted.Through this example introduced the design method in practical application about data dependencies in relation database and the programming process about internal deoendencies and external dependencies in this example.