/**
*  无级递归分类
*  @param  int   $assortPid  要查询分类的父级id
*  @param  mixed  $tag     上下级分类之间的分隔符
*  @return string $tree    返回的分类树型结构结果 
*
*/
function recursiveAssort($assortPid, $tag = \'\')
{  
  $assort = M(\'goods_class\')->where(\"class_pid = $assortPid\")->field(\'class_id, class_name\')->select();
  foreach ($assort as $value) {
    $tree .= \'<option value=\"\' . $value[\'class_id\'] . \'\">\' . $tag . $value[\'class_name\'] . \'</option>\';
    $tree .= recursiveAssort($value[\'class_id\'], $tag . \' \');
  }
  return $tree;
}