laravel 先orderBY再groupby，导致分组后的排序不正确

    

     

      

       

      
      

       
 //联系过我的经纪人
       
      
     

      

       

      
      

       
            $appletChats=$this->AppletChat->orderBy('created_at','desc')->where([['user_id',$param['user_id']],['source',2]])
       
      
     

      

       

      
      

       

                        ->get(['send_user','created_at'])->toArray();
       
      
     

      

       

      
      

       
            // 二维数组去重
       
      
     

      

       

      
      

       
            $res = array();
       
      
     

      

       

      
      

       
            foreach ($appletChats as $value){
       
      
     

      

       

      
      

       
                if (!empty($value['send_user'])) {
       
      
     

      

       

      
      

       
                    if (!isset($res[$value['send_user']])) {
       
      
     

      

       

      
      

       
                        $res[$value['send_user']] = $value;
       
      
     

      

       

      
      

       

                            }
       
      
     

      

       

      
      

       

                        }
       
      
     

      

       

      
      

       

                    }
       
      
     

      

       

      
      

       

                    dd($res);