中文摘要：

如何清晰的表示数据项之间的关系,进而了解数据之间更深层的内在关系,在当前的需求分析中没有明确的方法,但是其对于软件需求中数据的获取和数据关系的表示具有重要作用.如何通过数据本身采用推导的方法获取软件系统所必须的数据以及数据项,在当前的需求分析和获取方法中也没有直接方法和思路.本文采用数据源向图的方法,通过推导的方法获取必要的数据和数据项,并通过它来表示数据中各个数据项之间的关系,使得数据项之间关系的表示更加清晰,数据项的获取更加容易.

英文摘要：

How to unambiguously represent the relationship between data items and then extract the deeper level relationship between them is playing an important role in requirement engineering,but good methods for it doesn′t exist in current requirement analysis methods.At present there also doesn′t have method or thoughts for how to extract the data and data item of software system from data of requirement by deduce.In this paper,we use the method of Data Floating Direction Chart（DFDC） to extract the necessary data and data item for software systems and to represent the relationship between data items.The DFDC can make representation of relationship between data items more clearly and extraction process of data items more easily.