Refresh a value from a table in JavaScript

Seems you have your script inside a loop?

If so you will have

<div id="Enchere_<?php echo $MyId; ?>"></div>
<script>
$(document).ready(function() {
	setInterval(function() {
		$('#Enchere_<?php echo $MyId; ?>').load('refresh.php');
	}, 1000);
});
</script>
<div id="Enchere_<?php echo $MyId; ?>"></div>
<script>
$(document).ready(function() {
	setInterval(function() {
		$('#Enchere_<?php echo $MyId; ?>').load('refresh.php');
	}, 1000);
});
</script>
<div id="Enchere_<?php echo $MyId; ?>"></div>
<script>
$(document).ready(function() {
	setInterval(function() {
		$('#Enchere_<?php echo $MyId; ?>').load('refresh.php');
	}, 1000);
});
</script>

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and that is not a great idea. IDs need to be unique

You also may need to bust the cache for refresh.php by adding a random value to the call

I don't know if I got it right, but you want me to get the refresh call out of the loop?

<?php try{$Stat = $pdo->query("SELECT * FROM tb_shop_enchere"); while($data = $Stat->fetch(PDO::FETCH_ASSOC)) { $MyId = $data["NumId"]; ?>

<div id="Enchere_<?php echo $MyId; ?>"></div>

<?php }}catch(PDOException $e){echo "<div class='alert alert-danger'>".$e->getMessage()."</div>";} ?>

<script>
$(document).ready(function() {
setInterval(function() {
$('#Enchere_<?php echo $MyId; ?>').load('enchere-refresh.php');
}, 1000);
});
</script>

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enchere-refresh.php

<?php echo $data["Enchere_Max"];?>

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If this example is what you are asking, how should I tell <?php echo $data["Enchere_Max"]; ?> Which belongs to the identifier $MyId?

I'm really lost there ...

I am not sure you want to do it that way

What does refresh.php do?

Can it be passed an ID or perhaps passed an array of IDs and return all of them? It is not clear from your code what the contents of each div is. 

Can you show me what you expect to see on the page and what refresh returns?

Perhaps you mean something like this (not tested - may need some work with closures)

let tId = {};
$(function() {
  $(".escherir").on("click",function() { // any click on a button with class = escherir
    const $div = $(this).closest("div[id^=Enchere]");
    const id = $div.attr(id); // the container ID
    cont val = $div.find("input").val(); // I do not know the input field - so change if needed
    clearInterval(tId[id])
    tId[id] = setInterval(function() { $(id).load("refresh.php?myId="+id+"&val="+val },1000);
  });
)};

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Ok... That is two server calls per second. Why not call one server process that returns two values, one for  Enchere and one for  Nombre

You're absolutely right.
But I'm not really good at js or ajax ...
Here is the refresh.php page :

<?php
if(isset($_GET['MyRef'])){
$MyRef = htmlspecialchars($_GET['MyRef']);

$Stat = $pdo->query("SELECT MAX(Enchere) AS Enchere FROM tb_shop_enchere_liste WHERE Reference='".$MyRef."' ");
while($data = $Stat->fetch(PDO::FETCH_ASSOC)){

echo number_format($data["Enchere"] / $MNY_Taux, 0, ',', ' ')." ".$MNY_Franc;

}}
?>

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and the numbers page ... 

<?php
if(isset($_GET['MyRef'])){
$MyRef = htmlspecialchars($_GET['MyRef']);

$Nombre = $pdo->query("SELECT COUNT(NIC_Handle) FROM tb_shop_enchere_liste WHERE Reference='".$MyRef."' ")->fetchColumn();

if($Nombre > 1) {$Nbr = $Nombre." enchères";} else {$Nbr = $Nombre." enchère";}

echo $Nbr;

}
?>

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 both have two different tables.

What do you offer me?

I do not know PDO, but I assume you will get ONE max value back from the loop

If you have something like this

<?php
if(isset($_GET['MyRef'])){
  $MyRef = htmlspecialchars($_GET['MyRef']);
  $enchere = 0;

  $Stat = $pdo->query("SELECT MAX(Enchere) AS Enchere FROM tb_shop_enchere_liste WHERE Reference='".$MyRef."' ");
  while($data = $Stat->fetch(PDO::FETCH_ASSOC)){
    $enchere = number_format($data["Enchere"] / $MNY_Taux, 0, ',', ' ')." ".$MNY_Franc;
  }}
  $Nombre = $pdo->query("SELECT COUNT(NIC_Handle) FROM tb_shop_enchere_liste WHERE Reference='".$MyRef."' ")->fetchColumn();
  if($Nombre > 1) {$Nbr = $Nombre." enchères";} else {$Nbr = $Nombre." enchère";}

  echo '{ "enchere":"'.$enchere.'", "nbr":"'.$Nbr.'"}';

}
?>

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then you can do something like

let tId;
const ref = "<?php echo $MyRef; ?>";
$(function() {
  tId = setInterval(function() {
    $.get("refresh.php?MyRef="+ref+"&rnd="+new Date().getTime(),function(data) { // rnd is to bust the cache
      $('#Enchere_'+ref).html(data.enchere);
      $('#Nombre_'+ref).html(data.nbr);
    });
  }, 1000);
});  

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