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Foreign Key

When you create a relationship between entities, the primary key attributes of the parent entity are automatically migrated to the child entity. The designator (FK) indicates the name of the migrated key attribute, also known as a foreign key. This migration occurs automatically in the physical model.

If the foreign key attribute has the same name as an owned attribute in the child entity, the two instances are automatically unified into one attribute because it assumes that they are the same attribute. The process of combining or unifying identical attributes in an entity is called unification.

Note: The foreign keys display in the model by default, designated by (FK). If you do not see this designation, open the Diagram Editor (click Diagrams in the Diagram menu), and do the following depending on whether you are working in a logical or physical model:

Logical model

Click the Entity tab, and ensure the options Display Logical Foreign Key (FK) Designator and Display Migrated Attributes are selected.

Physical model

Click the Table tab, and ensure the option Display Physical Foreign Key (FK) Designator is selected.