Module_OOP_ORM::id_field_name

public function id_field_name()
{
    if ( false===$this->_id_field )
    {
        # 获取ID字段名
        $tmpdata = $this->create();
        $this->_id_field = $tmpdata->id_field_name();
        unset($tmpdata);
    }
    return $this->_id_field;
}