How to populate value from EXM_CARD_HOLDER_DETAILS in expense line DFF?

Summary:

We need to include CARD_HOLDER_IDENTIFICATION from EXM_CARD_HOLDER_DETAILS on our corporate card expense items. I have created a DFF to hold this value, but I am not sure how to write the proper SQL statement.

select card_holder_identification from exm_card_holder_details ch where ch.card_id = (select card_id from exm_expenses where expense_id = <expense_id of this expense item>)

What do I need to do to get <expense_id of this expense item>?

We need to pass this value to AP invoice for a business requirement.

Update 3/28/24 - I have been informed that it is not possible to reference the current row in DFF SQL statement.