Why check both isset() and !empty()

Question

Is there a difference between isset and !empty. If I do this double boolean check, is it correct this way or redundant? and is there a shorter way

Answer 1

if we use same page to add/edit via submit button like below

then we should not use

isset($_POST['edit_id'])

bcoz edit_id is set all the time whether it is add or edit page , instead we should use check below condition

!empty($_POST['edit_id'])