update query with concat in mysql using php

public function UpdateMyTask($Request,$user_id)
{
  $Query='';
  //$Request['ip_addr']=$_SERVER['REMOTE_ADDR'];
    //$Request['user_agent']=$_SERVER['HTTP_USER_AGENT'];
   // $user_agent= strlen(stristr($_SERVER['HTTP_USER_AGENT'],"Mobile"))?"Mobile":strlen(stristr($_SERVER['HTTP_USER_AGENT'],"Windows"))?"Windows":"Android" ; 
   if(strlen(stristr($_SERVER['HTTP_USER_AGENT'],"Mobile")))
{
  $user_agent="Mobile";
}else if(strlen(stristr($_SERVER['HTTP_USER_AGENT'],"Windows")))
{
  $user_agent="Windows";
}else if(strlen(stristr($_SERVER['HTTP_USER_AGENT'],"Android")))
{
  $user_agent="Android";
}
foreach($Request as $Index => $Value)
{
     if($Index == 'task_id')
    {
        $task_id= ($Value);
    }
	$Query.=$Index."='".mysqli_real_escape_string($this->link,$Value)."',";
}
$Query= rtrim($Query,',').",update_date_time=concat(update_date_time,',','".date('H:i')."'),ip_addr=concat(ip_addr,',','".$_SERVER['REMOTE_ADDR']."'),user_agent=concat(user_agent,',','".$user_agent."') where task_id='".$task_id."' and user_id='".$user_id."'";
$Query="update mytask set ".$Query;
	
		$result=$this->NonQuery($Query);
	
		return $result ;
	
}