Mapping Relationships to Existing Tables

If you engineer entity beans from database tables, foreign keys are interpreted as EJB relationships. However, if you have existing entity beans and existing database tables, you will need to map the relationships accordingly.

To map entity beans relationships, you use the Relationship Mappings editor.

To map entity beans to tables:

  1. If you have not already done so, establish a connection to the database schema(s) you want to use.
  2. In the Navigator, right-click on an entity bean and choose Edit CMP Mappings.
    The CMP Field Mappings editor opens.
  3. Click on the Relationship Mappings tab.
  4. Use the CMP Relationship Mappings editor to map relationships.
    Note that the Association Table checkbox may become selected by default under some circumstances (changing a table name, for example). This happens because the mapping tool tests for whether an association table is being used by comparing the table specified in the collection-mapping (1 end of a 1:* relationship) with the table used by the * end of the CMP field mapping. If they are different, the mapping tool indicates an intersection table is being used, though it may be detecting pre-existing field mappings.
    For additional help in the editor, click Help in the dialog or press F1.
    5. Note that a single column can map to both a CMP field and a CMR field, but a field is either
    CMP or CMR but not both. For compound primary keys, one field may be mapped to a CMP field and the other to a CMR field.
  5. If you need to define additional relationships, double-click any EJB in the Navigator to open the EJB Module Editor. For additional help in the editor, click Help in the dialog or press F1.
Related topics

Creating a Diagram of Enterprise JavaBeans
Developing Enterprise JavaBeans
What are Enterprise JavaBeans?

 

 

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