/**
* 無級遞歸分類 TP框架
* @param int $assortPid 要查詢分類的父級id
* @param mixed $tag  上下級分類之間的分隔符
* @return string $tree 返回的分類樹型結構結果 
*
*/
function recursiveAssort($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;
}