i'm trying to update a product in this table called 'livre' using this php code but i keep getting the message "Erreur!! La modification a échoué

I'm working on this project where i make a page online you can add ,update and show products on , and I'm trying to update a product in this table called 'livre' through the code down below ,but its not happening, I tried this code before on another table and it worked but this time i cant figure out the problem I keep getting the message "Erreur!! La modification a échoué.",please help me find the error.

  $the_photo=file_get_contents($_FILES['photo']['tmp_name']);

if(empty($_POST["code_l"])  ||  empty($_POST["titre"])||  
empty($_POST["aut"])  ||  empty($_POST["an_edi"]) || 
empty($_POST["edit"])  ||  empty($the_photo)  || empty($_POST["code_la"])  || 
empty($_POST["cdom"]))

{
    echo' Il faut saisir un code <br/>';
}

else
{
$code=$_POST["code_l"];
$titre=$_POST["titre"];
$aut=$_POST["aut"];
$an_edi=$_POST["an_edi"];
$edit=$_POST["edit"];
if(isset($_FILES["photo"])){
$photo = file_get_contents ($_FILES["photo"]['tmp_name']);
}
 $code_la=$_POST["code_la"];
 // 
 $cdom=$_POST["cdom"];
 try{
   $sql = "UPDATE livre set code_livre='".$code."',titre='".$titre."', auteur='".$aut ."', 
   anneé_editionint='".$an_edi."', 
   editeur='".$edit."',photo='".addslashes($photo)."',code_langue='".$code_la."',
    code_domaine='".$cdom."'  WHERE code_livre=".$code;

  $requete = $conx->prepare($sql);
  $stmt=$requete->execute();


   if($stmt === false)
     {
        die("Erreur!! La modification a échoué.");
    }
    else
     { header("location:lister_livre.php")  ;   }
 }
    catch (PDOException $e)
        {
        echo $e->getMessage();
        }
 }

'''