YOUR TURN TO PLAY

In the diagram, select the Attendance entity, and then select Identifier_1. Now double-click Identifier_1 to open the identifier’s property sheet. In the ‘Attributes’ tab, use the Add Attribute tool to add Attendance Date.

 

YOUR TURN TO PLAY

The entity Class needs an additional identifier that references the Short Name attribute; we can also create this via the entity symbol. On the diagram, select Class, then select Identifier_1. Now right-click Identifier_1, select Edit, and then select Insert. A new identifier will appear on the symbol. Edit the identifier name, and press <Enter> when you’re ready. Use any of the approaches you’ve used before to add the attribute Short Name to the new identifier. You can also create an identifier in the symbol by pressing <Ctrl+I> after selecting Identifier_1.

  This approach will work for any sub-object; just select an existing sub-object of the required type, first.

Now that we have created all the identifiers, your diagram will look something like Figure 14.25.

Figure 14.25 The finished diagram

14.25.emf

 

Key Points

·         PowerDesigner uses the word ‘identifier’ in the CDM and LDM, and ‘key’ in the PDM.

·         The easiest way to create a primary identifier/key is to check the ‘P’ column in a list of attributes or columns.

·         PowerDesigner allows you to choose which identifier/key a relationship/reference uses to migrate attributes or columns.

·         In the LDM, choose your template for constructing the name of migrated attributes; make sure you have a policy for this.

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