Era una prova che ho già fatto... ma quando invio il for la pagina non cambia... ti faccio vedere il codice:
codice:
<?php $data=date("Y/m/d");
include '../include/db_conn_open.php';
$query_fornitore = "SELECT fornitore FROM `oggetto` WHERE eliminato =0 group by fornitore";
$rs_fornitore = $mysqli->query($query_fornitore);
?>


<html>
<head>


<script>
function showUser(str) {
    if (str == "") {
        document.getElementById("txtHint").innerHTML = "";
        return;
    } else { 
        if (window.XMLHttpRequest) {
            // code for IE7+, Firefox, Chrome, Opera, Safari
            xmlhttp = new XMLHttpRequest();
        } else {
            // code for IE6, IE5
            xmlhttp = new ActiveXObject("Microsoft.XMLHTTP");
        }
        xmlhttp.onreadystatechange = function() {
            if (this.readyState == 4 && this.status == 200) {
                document.getElementById("txtHint").innerHTML = this.responseText;
            }
        };
        xmlhttp.open("GET","search_fornitore.php?q="+str,true);
        xmlhttp.send();
    }
}
</script>


<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<script src="https://ajax.googleapis.com/ajax/libs/jqueryui/1.12.1/jquery-ui.min.js"></script>
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css" integrity="sha384-BVYiiSIFeK1dGmJRAkycuHAHRg32OmUcww7on3RYdg4Va+PmSTsz/K68vbdEjh4u" crossorigin="anonymous">
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap-theme.min.css" integrity="sha384-rHyoN1iRsVXV4nD0JutlnGaslCJuC7uwjduW9SVrLvRYooPp2bWYgmgJQIXwl/Sp" crossorigin="anonymous">
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/js/bootstrap.min.js" integrity="sha384-Tc5IQib027qvyjSMfHjOMaLkfuWVxZxUPnCJA7l2mCWNIpG9mGCD8wGNIcPD7Txa" crossorigin="anonymous"></script>
<link rel="stylesheet" href="https://ajax.googleapis.com/ajax/libs/jqueryui/1.12.1/themes/smoothness/jquery-ui.css">
</head>
<body>


 <br /><br />
           <nav class="navbar navbar-default">
  <div class="container-fluid">
    <div class="navbar-header">
      
    </div>
    <ul class="nav navbar-nav">
    <li ><a href="../amministrativo/index.php">DASHBOARD</a></li>
    </ul>     
</nav> 


<table class="table table-striped" border="1" id="tabella">
<tbody>
<tr class="product">
<td>


<div class="form-group">
  <label for="sel1">Seleziona un Fornitore:</label>
  <select class="form-control" id="users" name="users" onchange="showUser(this.value)">


<option value="">-</option>
<?php
while($riga = $rs_fornitore->fetch_assoc()){


?>
  
  <option value="<?php echo $riga['fornitore'] ?>"><?php printf($riga['fornitore']) ?></option>
<?php } ?> 
  </select>


</tr>
</tbody>
</table>
</div>
<br>


<div id="txtHint">
<b>&nbsp;&nbsp;&nbsp;Elenco Prodotti:</b></div>
</body>
</html>
Il select e la generazione della pagina funziona prendendo i dati da questa pagina:
codice:
<!DOCTYPE html>
<html>
<head>
 <script src="https://ajax.googleapis.com/ajax/libs/jquery/2.2.0/jquery.min.js"></script>  
           
 <link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.6/css/bootstrap.min.css" />  
 <script src="../js/jquery.dataTables.min.js"></script>  
 <script src="https://cdn.datatables.net/1.10.12/js/dataTables.bootstrap.min.js"></script>            
 <link rel="stylesheet" href="https://cdn.datatables.net/1.10.12/css/dataTables.bootstrap.min.css" />  
      
</head>
<body>


<?php
$q = $_GET['q'];




$sql="select oggetto.id_merce as merce, fornitore, articolo, magazzino.id_merce, oggetto.prezzo_o,  descrizione, un_misura, fornitore, sum(quantita_m) as tot
from oggetto
inner join carico on oggetto.id_merce=carico.id_merce
inner join magazzino on carico.id_car=magazzino.id_car


where oggetto.eliminato = 0
and
carico.eliminato=0
and
quantita_m > '0'
and
fornitore = '$q'




group by magazzino.id_merce";
$rs = $mysqli->query($sql);
 


echo " 


<div class=\"container\">  
 
<div class=\"table-responsive\"> 
<table id=\"oggetto\" class=\"table table-striped table-bordered\"> 
 <thead> 
<tr>
<th>Selezione</th>
<th>Articolo</th>
<th>Descrizione</th>
<th>Un. Misura</th>
<th>Fornitore</th>
<th>Prezzo</th>
<th>Giacenza</th>
<th>Quantita'</th>


</tr>
</thead> 


<form name='modulo' action='ordine_inserito.php' method='post'>
";


$iterazioni_form=0;
while($riga = $rs->fetch_assoc()) {
    echo "<tr>";
	
	echo "<td><div class=\"checkbox\">
 		 <label><input type='checkbox' id='checkbox' name='checkbox'></label>
	     </div></td>"; 
	echo"<input type='hidden' id='id' name='id' value='".$riga['merce']."'/>"; 
    echo "<td> " .$riga['articolo']. "</td>";
	echo "<td>" .$riga['descrizione']. "</td>";
    echo "<td>" .$riga['un_misura']. "</td>";
    echo "<td>" .$riga['fornitore']. "</td>";
    echo "<td>" .$riga['prezzo_o']. "</td>";
	echo "<td>" .$riga['tot']. " ".$riga['un_misura']."</td>";
    echo "<td> <input type='text' id='ordine' name='ordine'  size='7' /> </td>"; 
  
    echo "</tr>";
	$iterazioni_form++;
}


echo "</table> 


<input type='hidden' id='iterazioni_form_aggiuntivi' name='iterazioni_form_aggiuntivi' value='".$iterazioni_form."'>
<button type='submit' class='btn btn-success'>INVIA ORDINE</button>
</form>
";




?>


</body>
</html>
Il problema è che non riesco ad inviare dati via form... Cosa sbaglio?