Implementing a One-to-Many Self-Relationship

Some object models require a class to reference another instance of the same class. In the advanced tutorial, a manager can have a collection of managed employees (see Figure B-1).

To map the managedEmployee attribute:

1. 
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   Select the Employee's managedEmployees attribute in the Navigator pane, then click the One-to-Many Mapping button on the mapping toolbar.

   The Editor pane displays the appropriate information for a one-to-many relationship to be specified.

2. Use the Reference Descriptor drop-down list to choose Employee.

   Figure B-34 One-to-Many Mapping General Tab

   
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3. Select the Use Indirection option, and choose ValueHolder. See "Implementing Indirection in the Tutorial".

4. Click the Table Reference tab. Use the Table Reference drop-down list to choose the EMPLOYEE_EMPLOYEE table (previously created in "To map the manager attribute:").

   • Click the Add button on the Table Reference tab to add a foreign key relationship.

   • Set the Source Field (foreign key) to MANAGER_ID.

   • Set the Target Field (primary key) to EMP_ID.

   Figure B-35 One-to-Many Mapping Table Reference Tab

   
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5. 
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   Click Save on the toolbar or choose File >  Save Project to save the project.