Populating drop down from MySQL table

I have writen some some code that uses frm_setup_new_fields_vars to populate a drop down menu with values from a MySQL table.

Is it possible to autopopulate some other fields based on the users selection from the drop down?

e.g user selects a person A, the address field is populated with person A's address details. If the user selects a Person B the address field is updated with person b's address.

Tthanks in advance.