Entity-Relationship Diagrams (ERDs) come in 3 types in general. They describe data models on 3 levels of abstraction – conceptual, logical and physical, ranging from high-level ideas to details required for implementation. With Visual Paradigm products (e.g. VP-UML), you can systematically and easily progress through these stages of development in data modeling.
Far from a copy & paste function only, you can actually develop a logical or physical design from a conceptual diagram, with the design tracing ability.
For example, if a new staff comes on board to work on a project’s physical design ERD, he/she can click on a database table to trace where this idea originally comes from in the conceptual diagram (to which it is inherently linked by VP-UML). This function will not only bring relief to the staff but also help safeguard the project’s quality along the way.
In this article, we will show you an example on how to create a conceptual ERD and transit it to a physical ERD, from which you can generate a DLL file for database implementation.
Note : VP-UML is used in the the following example. For simplicity reason, we will demonstrate how to go from conceptual design to physical design only, skipping the logical design.
Steps to Create a Conceptual ERD
1. In Visual Paradigm for UML (VP-UML), select the Model Explorer.
2. In the Model Explorer, right click on the project node untitled to select Model > New Model…
3. In the Model Specification dialog box (under the General tab), enter Conceptual Model for Name. Click OK.
4. In the Model Explorer, right click on Conceptual Model to select Diagram > Database Modeling > Entity Relationship Diagram.
5. Rename the new diagram to Sales Order Conceptual Design. Select the radio button of Conceptual Model for Data Model.
6. Create the following conceptual ERD as shown below.
Steps to Create (“Transit to”) a Physical ERD from a Conceptual ERD
1. Right click on the background of the diagram to select Utilities > Transit to Physical ERD…
2. In the Select Parent Model of New Physical ERD dialog box, select untitled and click New Model.
3. In the Model Specification dialog box (under the General tab), name it Physical Model. Click OK.
4. You should see a new entry Physical Model. Click OK.
5. A physical model is generated as shown below.
If you look at the Property Pane, you should see Physical in the Data Model field. That’s how we know it’s a physical model diagram.
As an example, you may then begin refining the physical model to something like this.
Steps to Trace the Transit Origin
Let’s say you want to check the origin of the database table Order in the physical design diagram.
1. Right click on Order in the Physical Model diagram to select Related Elements > Transit From
You’ll see Sales Order Conceptual Design.Order listed as the origin. If you select it, you’ll be taken back to the original conceptual design diagram.
2. The origin ( e.g. Order ) will appear selected in the conceptual design diagram.
Steps to Generate DLL File for Database Implementation
1. From the main menu, select Tools > Database > Generate Database…
2. In the Database Code Generation dialog box:
- select a Output Path (the location where the resulting .DLL file will be saved)
- Select the checkbox Generate DLL
- Click OK
Note: If you have not configured your database yet, you’ll be asked to do so before the DLL file gets generated.