Stuff

		$catId = 0;
$list = "<select name=\"REMOVE ME WHEN PUT IN FUNCTION\">";
        $sql = "SELECT cat_id, cat_parent_id, cat_name
                        FROM tbl_category
                        ORDER BY cat_name";
        $result = dbQuery($sql) or die('Cannot get category. ' . mysql_error());
        while($row = dbFetchAssoc($result)) {
			extract($row);
			if ($cat_parent_id == 0){
			$list .= "<optgroup label=\"$cat_name\">"; 	
                $sql2 = "SELECT cat_id, cat_parent_id, cat_name
                        FROM tbl_category
						WHERE cat_parent_id = $cat_id
                        ORDER BY cat_name";
				$result2 = dbQuery($sql2) or die('Cannot get subcategory. ' . mysql_error());
				while($row = dbFetchAssoc($result2)) {
						extract($row);
				$list .= "<option value=\"$cat_id\" ";
						if ($cat_id = $catId){ 
						$list .= "checked";
						}
						$list .=">$cat_name</option>";
				}
			$list .= "</optgroup>";


        }
}	
			$list .= "</select>";	
        echo "$list";