Progressively Develop Conceptual, Logical and Physical ERDs July 29, 2011

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.

Select the Model Explorer Tab

Select the Model Explorer Tab

2. In the Model Explorer, right click on the project node untitled to select Model > New Model…

Select Model to New Model

Select Model to New Model

3. In the Model Specification dialog box (under the General tab), enter Conceptual Model for Name. Click OK.

Name Conceptual Model in Dialog Box

Name Conceptual Model in Dialog Box

4. In the Model Explorer, right click on Conceptual Model to select Diagram > Database Modeling > Entity Relationship Diagram.

Right Click to Select Entity Relationship Diagram

Right Click to Select Entity Relationship Diagram

5. Rename the new diagram to Sales Order Conceptual Design. Select the radio button of Conceptual Model for Data Model.

Rename Conceptual Design Diagram

Rename Conceptual Design Diagram

6. Create the following conceptual ERD as shown below.

Conceptual ERD Sample

Conceptual ERD Sample

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…

Select Transit to Physical ERD

Select Transit to Physical ERD

2. In the Select Parent Model of New Physical ERD dialog box, select untitled and click New Model.

Select the Parent Model to Create a New Model

Select the Parent Model to Create a New Model

3. In the Model Specification dialog box (under the General tab), name it Physical Model. Click OK.

Name the Physical Model Dialog Box

Name the Physical Model Dialog Box

4. You should see a new entry Physical Model. Click OK.

Physical Model Fresh in Dialog Box

Physical Model Fresh in Dialog Box

5.  A physical model is generated as shown below.

Physical Model Generated by Transit Function

Physical Model Generated by Transit Function

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.

Data Model Property - Physical

Data Model Property – Physical

As an example, you may then begin refining the physical model to something like this.

View of Refined Physical Model

View of Refined Physical Model

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.

Right Click to Check Transit From

Right Click to Check Transit From

2. The origin ( e.g. Order ) will appear selected in the conceptual design diagram.

Takes You Back to Transit Origin

Takes You Back to Transit Origin

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.

Database Code Generation Dialog Box

Database Code Generation Dialog Box

 

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