DFD和ERD的区别

1. 数据流图(DFD)：
数据意味着信息，流意味着移动，图意味着用图片来表示某事。因此，DFD 只是数据或信息流的图形表示。它是数据系统的框架或模式。它包括数据输入、数据输出、存储数据。 DFD 描述了将数据作为输入、存储数据、将数据作为输出的过程。 DGD 描述了完成该过程的数据路径。

DFD主要有两种类型：物理数据流图和逻辑数据流图。

DFD 示例——柠檬水摊

2.实体关系图(ERD)：
ERD 也称为实体关系模型。 ERD 最初是由 Peter Chen 提出的。实体是指用于存储信息且可区分的任何对象，关系是指连接，图/模型是指用于表示某物的图片。因此，ERD 只是用于表示或显示存储在数据库中的实体或数据对象之间关系的图表或模型。 ER 模型的主要组件是实体、属性和关系。这是表示数据库设计的一种非常简单的方法。

ERD 示例——学校信息管理

DFD和ERD的区别：

S.No.	DFD	ERD
1.	It stands for Data Flow Diagram.	It stands for Entity Relationship Diagram or Model.
2.	Main objective is to represent the processes and data flow between them.	Main objective is to represent the data object or entity and relationship between them.
3.	It explains the flow and process of data input, data output, and storing data.	It explains and represent the relationship between entities stored in a database.
4.	Symbols used in DFD are: rectangles (represent the data entity), circles (represent the process), arrows (represent the flow of data), ovals or parallel lines (represent data storing).	Symbols used in ERD are: rectangles (represent the entity), diamond boxes (represent relationship), lines and standard notations (represent cardinality).
5.	Rule followed by DFD is that at least one data flow should be there entering into and leaving the process or store.	Rule followed by ERD is that all entities must represent the set of similar things.
6.	It models the flow of data through a system.	It model entities like people, objects, places and events for which data is stored in a system.