Chapter 2 Physical Data Model Basics

Creating a PDM

You can create a new PDM from scratch, or reverse engineer the model from an existing database.

For information about reverse engineering, see the "Reverse Engineering a Database into a PDM" chapter.

To create a new PDM:

1. Select File→New to display the New dialog box.
   
2. Select Physical Data Model in the list of model types.
3. Select one of the following radio buttons:
   
   
   • New model – Creates a new, standard, model.
   • New model from template – Creates a model from a model template. A model template is a set of model options, display preferences, extension, or objects saved in a model located in the template folder. You use model templates when you need to reuse preferences and options in several models.
     
     For more information about model templates, see the "Creating a model" section in the "Managing Models" chapter , in the General Features Guide .
4. Type a model name in the Model name box. The code of the model, which may be used for script or code generation, is derived from this name according to the model naming conventions.
5. Select a DBMS from the list.
   
   DBMSs are defined in dedicated XML files (with a .xdb extension), which are provided as part of your PowerDesigner installation in the "\Resource Files\DBMS" directory, and contain all the syntax and specifications for each target DBMS.
6. Select one of the following radio buttons:
   
   
   • Share the DBMS definition – use the original DBMS file in the "Resource Files\DBMS" directory. Any changes made to the DBMS are shared by all linked PDMs.
   • Copy the DBMS definition in model – make a copy of the original DBMS file in the "Resource Files\DBMS" directory. The current DBMS is independent of the original DBMS, so modifications made to the DBMS in the DBMS directory are not available to the PDM. The copied object language is saved with the PDM and cannot be used without it.
     
     For more information on DBMS properties and customizing a DBMS, see the "DBMS Reference Guide" chapter in the Advanced User Documentation .
7. Select the type of the first diagram in the First Diagram list. The first type of diagram selected remains in memory, and is the default for the next time when you create a new PDM.
   
   You can create as many diagrams as you need in the same PDM. They are sorted alphabetically in the Browser, except the diagram specified here, which is always the first in the list.
8. [optional] If you want to attach one or more extended model definitions to complement the selected DBMS, click the Extended Model Definitions tab, and select the extended model definitions of your choice.
   
   For more information on attaching extended model definition to a model, see the "Extended Model Definitions Reference Guide" chapter in the Advanced User Documentation .
9. Click OK to create the new PDM in the current Workspace.

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