request for features??

Don't know if this is the correct way to approach this, but if not can you advise correct route As a Foxpro programmer trying to migrate to PHP, Is it possible with PHP to automatically refresh some fields in a form based on a choice made from a combi/list box, something along the operation of the [valid()] clause in Foxpro & Access without having to click on the [submit] button I could do it using multiple similar hidden forms, but it's less user friendly than just clicking on an item (say "apples"), then automatically populating the next combi/list with "Granny Smith", "Golden Delicious" etc, and filling "unit of sale" & "Unit cost" text boxes with the last entered value. Then when the variety is redefined, refreshing again the "unit of sale" & "Unit cost" text boxes Any chance in later versions, or is it just not possible within the PHP framework?