Foreign keys

A foreign key relationship between two database tables is specified in the input model by adding a relationship of stereotype foreignkey (one word, no spaces) between two entity classes. Optionally, you can name the relationship. The relationship name is then applied to the foreign key constraint added to the database. Otherwise, the database chooses its own name for the constraint.

The following rules apply to using foreign keys:

• Foreign key relationships are allowed on entity classes only.
• Fields that are referenced by a foreign key are set to unique, as the unique field is required by some databases.
• If the foreign key references the primary key of another entity, the generator does not produce a redundant unique clause as the primary key is already unique.
• Foreign keys cannot be specified on subclass entities. You must specify the relationship by using the actual base entity classes themselves.