Comparing Database Schemas Visually

Overview

1. Make a copy of the current ERD (version 1.0).
2. Modify the ERD.
3. Compare the changes from version 1.0 to the latest version.

Here is the database design for the Computer Sales project. We will modify it and then compare it with the original copy.

Using Visual Diff

1. Download ComputerSales.vpp. You can also find this file at the bottom of this tutorial.
2. Open the downloaded .vpp file in Visual Paradigm. To open a project, select Project > Open from the application toolbar.
3. Let's make a copy of the existing project by selecting Project > Save > Save as from the application toolbar.
4. Name the new project ComputerSales_1_0.vpp and click OK.
   
5. Reopen the previous project by selecting Project > Open > ..\ComputerSales.vpp.
6. Make a few changes to the project. Rename the Addresses entity to Customer_Addresses.
   
7. Add a new column to the Computer_Part entity by right-clicking on it and selecting New Column from the main menu.
   
8. Enter discount : number(8, 2) as the column definition, press Enter, and then press Esc to confirm the edit.
   
9. Create an entity with a One-to-Many Relationship -> Entity relationship from Computer_Part. Name the entity Part_Usage.
10. Add the following columns to Part_Usage:
    
    • +id : number(10)
    • description : varchar2(1024)
    
    
11. Open Visual Diff by selecting Modeling > Visual Diff from the application toolbar.
    
12. In the Visual Diff window, uncheck Use Working Project on the left-hand side.
    
13. Click ..., select ComputerSales_1_0.vpp, and then select Computer Sales as the diagram.
    
14. Check Use Working Project on the right-hand side. Select Computer Sales as the diagram on the right-hand side.
    
15. The differences between the diagrams are listed at the bottom of the window.
16. Select the differences one by one to see the changes.
    
    • Addresses entity
      
    • New column
      
    • New associated entity