There are different database environments - Access, SQL, etc. The issue is to have some code that would first do a search to find out which databases exist; then pick all the field names within the tables of those databases and present those names on a GUI.
e.g. An Access database has a table 'A' with feilds 'a', 'b', 'c'. Another database in SQL has a table 'B' with fields 'x', 'y', 'z'.
The user clicks a button and as a result, a GUI appears showing all the fields names 'a', 'b', 'c', 'x', 'y', 'z'.