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The Difference Between Conceptual Model, Logical Model And Physical Model
- May 14, 2018 -

Conceptual model.

First, look at the explanation of the concept: in the process of cognition, human beings rise from perceptual knowledge to rational knowledge, abstract the common essential features of perceived things and generalize them, and become concepts.

So, what is the conceptual model? Conceptual models are your knowledge of things in the real world. He used to describe the system "what". Popularly speaking, a conceptual model is something that is abstracted to describe real life after the user's needs are understood.

In the software development tools, we have learned eight kinds of tools of conceptual models: block diagram, entity relation diagram, data dictionary, computer simulation model and so on.

For example, our entity relationship diagram is a generalization of our knowledge system from the real world.

Logical model.

First, let's get to know the word of logic first. Logic is the law of thinking. In popular terms, it is the order in which things are executed.

Second, what is the logical model? The logical model is to materialized the conceptual model, which is to realize what is described by the conceptual model, what specific functions are needed and what specific information is handled. The logical model describes the system "what to do". This is the refinement stage of demand analysis.

Still take the machine room charging system as an example: "student" information basically includes: school number, name, sex, contact, professional and other attributes; "card" information basically include: card number, school number, balance, type and other attributes. And we should confirm the relationship between students and cards. In addition, we have to set up several data tables: Student tables, card tables, etc. We also need to achieve functions such as registration, recharge, refund card, checkout and so on.

The logic model only explains what the system wants, but how to implement it and how to achieve it is not involved. The latter belongs to the category of the physical model.

physical model

Most of the physical models are unfamiliar to us. The physical model is based on the contents mentioned above, and is realized in specific physical media. The physical model describes how the system "does"

For example, the database can be built on the database server by using SQL Server 2008. Our computer room charging system can be developed by VS or VB, and then encoded.