DFD vs ERD
DFD and ERD are different data models that are mainly used for organizing business data for proper communication between members of a group.
DFD shows how data enter a system, are transformed in that system, and how it is stored in it. Meanwhile, ERD represents the entity model and will show what a system or a database will look like but not explain how to implement it.
DFD and ERD are formulated using different rules. With DFD, each of the processes and the storing should have at least one data flow going towards it and one leaving it. All the data must have to go through a certain process, and all the processes in a system should be linked to a data store or another process. With ERD, all the entities should represent a group of similar things. All the definitions in ERD should be unambiguous.
The DFD model is a multi-level representation that commences with abstract information and includes multiple decomposed levels. The ERD model represents the system data and includes an elaborate description of the relation between the data.
DFD is represented by ovals, rectangles, or circles and is named with a single word. Arrows represent the flow, and ovals or parallel lines represent the storings. The ERD is represented by a rectangular box, and diamonds represent the relationship between the entities. Cardinality is represented by lines or standard notions.
Both these data models also come with many different shortcomings. DFD is not enough to completely describe a system. Moreover, the use of different symbols can create confusion in the users. The DFD cannot also specify computations in a process. ERD does not show the interaction between the model or data and how it changes in a system.
Summary:
1.DFD shows how data enter a system, are transformed in that system, and how it is stored in it.
2.ERD represents the entity model and will show what a system or a database will look like but not explain how to implement it.
3.With DFD, each of the processes and storings should have at least one data flow going towards it and one leaving it.
4.With ERD, all the entities should represent a group of similar things. All the definitions in ERD should be unambiguous.
5.DFD is represented by ovals, rectangles, or circles and is named with a single word. The ERD is represented by a rectangular box.