Directory structure:

Stored as:
IdParentName
31Countries
43Belgium
53Netherlands
63Germany
75Business and Economy

Retrieve list with:

<?php
    
function gimmeParent($id) {
        global 
$dir;

        
$res mysql_query("SELECT parent, name FROM directory WHERE id = $id");
        if (
mysql_num_rows($res) > 0) {
            
$dir[] = ($row mysql_fetch_row($res));
            
gimmeParent($row['parent']);
        }
    }

    
gimmeParent(7);
?>