There are three types of ERDs: the conceptual, the logical, and the physical, which support modeling of data in three levels of abstraction from conceptual data model to implementation of a specific database. Starting from this new release, Visual Paradigm allows transition between these three levels models as well as to support traceability between them. You may create Conceptual Model and refine it into a logical model that are independent on any DBMS. Now, let's create a Conceptual ERD first:

1. Click on the Model Explorer tab.
   
2. Add a Conceptual Model by right clicking on the project node and selecting Model > New Model... from the popup menu.
   
3. In the Model Specification dialog box, input Conceptual as model name and click the OK button.
   
4. Create a Conceptual ERD by right-clicking the Conceptual model just created and selecting Diagram > Database Modeling > Entity Relationship Diagram from the popup menu.
   
5. A diagram is created. Input the diagram name.
   
6. A radio button box appear on the right hand side of the diagram pane indicating the type of model the diagram is belonging to. Make sure Conceptual Model is selected, which means that this diagram, as well as the entities that will be created in this diagram are part of the Conceptual Model.
   
7. Develop the Conceptual Model in the Conceptual ERD.
   
   
   Now Let's refine the Conceptual Model into a Physical Model.
   (Depending on the situation, you might want to refine the Conceptual ERD into a logical ERD and subsequently touch it up into a Physical ERD for implementation. We will skip the logical ERD and directly proceed to the Physical ERD for just demonstrating the ideas in fewer steps).
8. Right click on the diagram background of the Conceptual ERD and select Transit to Physical ERD... from the popup menu.
   
9. In the dialog box for parent selection, press New Model for creating a Physical Model.
   
10. Enter Physical as model name and press OK to confirm.
    
    
    This produce a Physical ERD which looks exactly the same as the Conceptual one.
    
11. Before we start changing anything on it, rename it first. Right-click on the diagram background and select Rename... from the popup menu.
    
12. Give a meaning name for this Physical ERD and press the Enter key to confirm.
    
13. Refine the transcribed Conceptual Model ERD into the Physical Model.
    For example: Adding more entities or modify some of the entities as desired.
    
14. We can trace the changes different levels with the help of Model Transitor. Take the Order entity as example, we can trace back to see how it looked like in the Conceptual Model.
    Right-click on the Order entity in the Physical ERD and select Model Transitor > Tranasit From > Sales Order Conceptual Design.Order in the popup menu.
    
15. The Conceptual ERD is opened, and the ordinary Order entity is selected.
    
    
    Note that model transition is a bi-directional relationship. You can trace back from Physical Model to Conceptual Model. Likewise, you can trace from Conceptual Model to Physical. To do so, follow the step as described in the previous step, but choose "Transit To" in the popup menu.

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