Exercise 6: Modifying transformation properties to roll down

Before you begin, you must complete Exercise 5: Modifying transformation properties to roll up.

In the last exercise you modified the HR.ldm logical data model to specify the roll up option. In this exercise, you will modify the HR.ldm again to specify the roll down option, and then transform again to a new physical data model. You will then observe how the changes to the generalization object properties affected the transformation.

To modify transformation properties to roll down:

  1. In the Data Project Explorer, expand the HR.ldm logical data model, the HR package, and the Diagrams folder.
  2. Double-click the HR entity diagram to open it in the diagram editor.
  3. In the diagram, select the link between the supertype EMPLOYEE and the subtype REGULAR.
  4. Customize the Transform as property for this generalization object by selecting Roll Down from the list.
  5. Select the link between the supertype EMPLOYEE and the subtype HOURLY and notice that the Transform as property for this generalization has also been changed to Roll Down.
  6. Save the HR.ldm logical data model.
  7. Repeat the steps in Exercise 4 to transform the HR.ldm logical data model to a new physical data model.

    In this case, specify HR_rolldown_pdm as the name for the new physical data model file, and HR_rolldown as the schema name.

  8. Repeat the steps in Exercise 4 to create a new overview diagram under the HR_rolldown schema and display column compartments in the diagram editor.
  9. Click the HR_rolldown tab in the editor area to see the diagram.
  10. Double-click the HR_rolldown tab to maximize the diagram editor view.

    Screen capture showing the HR_rolldown diagram in the diagram editor, as described.

    Notice the differences between this physical data model and the one that was created in the last exercise. In this case, the EMPLOYEE table was not created, and the REGULAR and HOURLY tables repeat the columns that were in EMPLOYEE. The Roll Down option is used for another type of denormalized pattern.

  11. Save and close the HR_rolldown_pdm.dbm file and the HR_rolldown diagram.

Now you are ready to begin Exercise 7: Modifying the physical data model and generating a DDL script.