Codeigniter 我想在函数read上添加一些给定的代码

我想添加这个代码

if(empty($this->session->userdata('isAdmin')))
{
    $this->db->where('user_id',$this->session->userdata('id'));
}

在函数

read（）

上。有人能帮忙吗

public function read()
{
    return $this->db->select("a.*,b.*,c.*,d.*")
           ->from("trip AS a")
           ->join('fleet_type AS b', 'a.type = b.id')
           ->join('trip_route AS c', 'a.route = c.id')
           ->join('shedule AS d', 'a.shedule_id = d.shedule_id')
           ->limit($limit, $start)
           ->get()
           ->result();
}

---

就这样把条件分开

    public function read ( ) {
     $this->db->select("a.*,b.*,c.*,d.*")
       ->from("trip AS a")
       ->join('fleet_type AS b', 'a.type = b.id')
       ->join('trip_route AS c', 'a.route = c.id')
       ->join('shedule AS d', 'a.shedule_id = d.shedule_id');

     if(empty($this->session->userdata('isAdmin'))) {
      $this->db->where('user_id',$this->session->userdata('id'));
     }

     $this->db->limit($limit, $start);
     $_result = $this->db->get()->result();

     return $_result;
    }

按照文档中的说明进行操作，如果不链接，则可以使用if子句