I have a list of patients who were seen in 2014 at one location. I want to query the database and look at all other locations and their patients. If the patients on my list from the one location have NOT been at any other location, I want those patients. However, if they have had a appointment at any other location, I do not want to see them.
This may sound easy to some, but I cannot figure out how to do it. I can figure out how to see the patients from the list who were seen in other locations, but not if they haven't been.
Is this even possible?