tp3无法select一条数据记录
select 用于找出多组数据
$config=$this->config_model->limit(1)->order('id asc')->select();
$this->assign('config',$config);
find用于找一条数据方便取出
$config=$this->config_model->limit(1)->order('id asc')->find();
$this->assign('config',$config);