/**
* 无级递归分类 TP框架
* @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;
}