ติดปัญหา การ UPDATE MYSQL 2 ตารางครับ รบกวนด้วยครับ

<?php

session_start();
//PUT THIS HEADER ON TOP OF EACH UNIQUE PAGE
if(!isset($_SESSION['id_user'])){
  header("location:login.php");
  header("Content-type: text/html; charset=utf-8");
}


include "config.php";




if(isset($_GET['u'])):
     if(isset($_POST['bts'])):

 $image_id = "";
  if(is_uploaded_file($_FILES['file']['tmp_name']))  {
    if($_FILES['file']['error'] == 0) {
      include "lib/IMager/imager.php";
      $img = image_upload('file');
      $img = image_to_jpg($img);
      $img = image_resize_max($img, 1000, 500); 
      $f = image_store_db($img, "image/jpeg");
      
      echo $sql = "UPDATE image SET  image_content='$f' WHERE  image_id ";
      mysqli_query($mysqli, $sql);
      $image_id = mysqli_insert_id($mysqli);
    }
  }

  echo $strSQL = "UPDATE article SET topic = '".trim($_POST['topic'])."' 
  ,article_text = '".trim($_POST['content'])."', writer = '".trim($_POST['writer'])."' WHERE article_id =".$_GET['u']." ";
  $objQuery = mysqli_query($mysqli,$strSQL);
  
   echo  "<div class='alert alert-success'>
          <span class='glyphicon glyphicon-info-sign'></span> &nbsp; บันทึกข้อมูลเรียบร้อยแล้ว !
          </div>";   




          endif;
     endif;



    $res = $mysqli->query("SELECT * FROM article WHERE article_id =".$_GET['u']);
     $row = $res->fetch_assoc();

?>