"php" help with menu bar

[romio]

Am currently working on php Product Catalogue system, DB is created and is running fine, small problem with the menu though, each category might have many sub_categories, and here were the problem starts, if i have cat_1 with sub cat_1_1 and cat_1_2 and cat_2 with sub cat_2_1 then codes works fine, i need to have a general function that would work on all depth, i cant just keep creating a new sql or a function code for every sub_categories! so i though of a recursive function or an array.. Any help would be appreciated.
[code]
function find_root_categories()
{
    $catID = $_GET['cat'];
        
        $find_parent_categories = "SELECT node.category_id ,node.name, (COUNT(parent.name) - 1) AS depth
        FROM categories AS node, categories AS parent
        WHERE node.lft
            BETWEEN parent.lft AND parent.rgt
        GROUP BY node.name
        HAVING depth=1 ORDER BY node.lft";
        
    $result_parent_categories = mysql_query($find_parent_categories);
    $num_rows_parent_categories = mysql_num_rows($result_parent_categories);

    if(!($num_rows_parent_categories))
        {
            echo"<tr>
                    <td valign=top align=center>No Records To Display</td>
                </tr>";
        }
            else
            {
                while($row = mysql_fetch_array($result_parent_categories))
                {
                      $name= $row['name'];
                      $catid = $row['category_id'];
                    echo"
                            <a href='?cat=$catid'>$name</a><br />
                        ";
                    if($catID == $catid){
                        
                        get_sub_cat($catID);
                    }
                }
            }
    
}
[/code]
[code]

function get_sub_cat($catID){
    
  
   $sql = "select * from categories where parent = $catID";
   $result = mysql_query($sql);
   $row = mysql_fetch_array($result);
      
   // now, retrieve all descendants of the $root node
   $result = mysql_query($sql);

    while($row = mysql_fetch_array($result))
    {
          $name= $row['name'];
          $catid = $row['category_id'];
        echo"
                &nbsp;&nbsp;&nbsp;<a href='?cat=$catid'>$name</a><br />
            ";
            if($catID == $catid){
                        get_sub_cat($catid);
            }
    }
}
[/code]