=============================== What are foreign keys used for? =============================== Foreign keys that you can create in the Application Builder prevent deletion of a record in the lookup table if a reference to it is stored in the lookup field. For example, when a foreign key is created on the "Customer" field for "Invoices" item, user won't be able to delete a customer in "Customers" catalog if a reference to it is stored in "Invoices". The soft delete attribute of the lookup item must be set to false (see :doc:`Item Editor Dialog ` ) for the lookup field to appear in the :doc:`Foreign Keys Dialog `