function get_cats_tree($conn) {
  $tree = array();
  $all_cats = array();


  $query = "SELECT id,parent,name FROM CATS";
  $stid = oci_parse($conn, $query);
  oci_execute($stid);

  while ($row = oci_fetch_assoc($stid)) {
    $all_cats[] = $row;
  }

  // Основная ветвь дерева категорий
  foreach ($all_cats as $key => $value)   {
    if(!$value['PARENT']) {
      $value['CHILDS'] = array();
      unset($value['PARENT']);
      $tree[$value['ID']] = $value;
      unset($all_cats[$key]);
    }
  }

  // Ветвь второго уровня
  foreach ($all_cats as $key => $value) {
    $parent = $value['PARENT'];
    unset($value['PARENT']);

    $tree[$parent]['CHILDS'][$value['ID']] = $value;
  }

  return $tree;

}