<?php while($row = $shops->fetch_assoc()) : ?>
<form method="post" action="project.php?id=<?php echo $id; ?>">
<input type="hidden" name="shop[]" value="<?php echo $row['id']; ?>">
<input type="text" name="boxposition[]" class="form-control" value="<?php echo $row['box_position']; ?>" style="width: 50px;">
<input type="submit" name="update" value="Update Order" class="btn btn-primary">
</form>
<?php endwhile; ?>

$shopid = $_POST['shop'];
$boxorder = $_POST['boxposition'];

foreach ($shopid as $index => $value) {
$query = "UPDATE shops SET box_position = '".$boxorder[$index]."' WHERE id = '".$shopid[$index]."'";
$update_row = $db->update($query);

echo $shopid[$index].'<br>';
echo $boxorder[$index].'<br>';