Hilary,
thanks for the quick response, I am trying to update a query field, so I only return the values for that user ID. After I posted the question, thinking I was stumped, I had an idea, I think near what you are suggesting, I should have put WAY more information in the original post (I blame the coffee, or lack thereof before posting). This is a query form that pulls back user information based on their user ID.
Create secondary data connection to same SQL table, retrieve on open
Create a temporary field with a default value of @customer_id[. = userName()]
set my query field (User ID) to that value, so if it is populated, the user ID fills in, otherwise, it is blank.