数据流程图画法(数据流程图)

数据流图是过程建模的一种工具,用于分析、描述信息系统的数据转换和流动状况,显示系统内所有的基本成份及其相互联系的概况和细节。数据流图概括描述系统的内部逻辑,是理解表达用户需求、与用户沟通交流的工具,是新系统逻辑模型的最重要组成部分。

数据流程图有四个部分组成：外部实体、处理过程、数据存储、系统中的数据流。

Data flow diagram is a tool of process modeling, used to analyze and describe the data conversion and flow status of the information system, and display all the basic components in the system and the overview and details of their interconnections. The data flow diagram summarizes the internal logic of the system. It is a tool for understanding and expressing user needs and communicating with users. It is the most important part of the new system logic model.

The data flow diagram consists of four parts: external entities, processing procedures, data storage, and data flow in the system.

外部实体是与系统交互的外部的人员、组织部门、其他系统或者其他组织，也称为源点/终点。外部实体中支持系统数据输入的实体称为源点，支持系统数据输出的实体称为终点。它说明了外部数据的来源和去处，指明了系统的边界。

External entities are external personnel, organizational departments, other systems, or other organizations that interact with the system, and are also referred to as source/end points. Among the external entities, the entity that supports system data input is called the source point, and the entity that supports system data output is called the end point. It explains the source and destination of external data, and points out the boundaries of the system.

信息系统中，过程是指对输入数据流或条件做出响应的工作，即对数据进行处理或者变换，因此也称为处理或者转换。系统中的过程大致可以划分为三类：一是功能过程，是一套和企业相关活动和正在进行的活动，功能没有开始和结束。二是事件过程，功能由响应事件的过程组成，事件必须作为一个完整的逻辑单位工作，也被称为事务，接受输入而触发其执行，对输入作出响应后，事件结束。三是基本过程，是指为了完成一个事件的响应所需要的离散的、详细的活动或任务。每一种过程又包括数据输入、数据处理和数据输出三个部分。系统本身也可以看做是一个过程。

In an information system, process refers to the work of responding to input data streams or conditions, that is, processing or transforming data, so it is also called processing or conversion. The processes in the system can be roughly divided into three categories:  The first is the functional process, which is a set of enterprise-related activities and ongoing activities. The function does not start and end. The second is the event process. The function is composed of the process of responding to the event. The event must work as a complete logical unit, also called a transaction. It accepts input and triggers its execution. After responding to the input, the event ends.  The third is the basic process, which refers to the discrete and detailed activities or tasks required to complete an incident response. Each process includes three parts: data input, data processing and data output. The system itself can also be seen as a process.

数据流是一个过程的数据输入或数据输出，是流动中的数据，是模拟数据在系统中传递过程的工具，也用于表示在文件或数据库中创建、读取、删除或修改数据。数据流可以汇合，组合数据流是由其他数据流构成的数据流。也可以分叉，分支的数据流是分成多个数据流的数据流，指示了一个数据流的所有或者部分到不同的目的地的路径。用来表示数据流值，但不能用来改变数据值。

Data flow is the data input or data output of a process. It is the data in the flow. It is a tool that simulates the process of data transmission in the system. It is also used to indicate the creation, reading, deletion or modification of data in a file or database. Data streams can be merged, and a combined data stream is a data stream composed of other data streams. It can also be branched. A branched data stream is a data stream divided into multiple data streams, indicating the path of all or part of a data stream to different destinations. Used to represent the data flow value, but cannot be used to change the data value.

数据存储是表示数据保存的地方，用来存储数据。系统过程从数据存储中提取数据，也将处理后的数据返回数据存储。与数据流不同的是数据存储本身不产生任何操作，它仅仅响应了存储和访问数据的要求。如果说数据流是运动中的数据，数据存储就是静止的数据，存储的数据一般以文件和数据库形式存在于系统中，它存储了所有实体的实例。数据存储一般是以下内容之一:个人或小组、地点、对象、事件、概念等。为避免数据流交叉，允许数据流图上重复出现相同的数据存储。

Data storage refers to the place where data is stored and is used to store data. The system process extracts data from the data store and returns the processed data to the data store. The difference with the data stream is that the data storage itself does not generate any operations, it only responds to the requirements of storing and accessing data. If data flow is data in motion, data storage is static data, and stored data generally exists in the system in the form of files and databases, and it stores instances of all entities. Data storage is generally one of the following: individuals or groups, locations, objects, events, concepts, etc. To avoid data flow crossing, the same data storage is allowed to appear repeatedly on the data flow graph.

参考资料：文字：《信息系统开发》；图片：百度；翻译：Google翻译

本文由LearningYard新学苑原创，部分图片文字来自网络，如有侵权请联系删除。