PHP e MYSQL

[Valeria89]

<?phprequire 'connessione.php';$db_selection = mysql_select_db('db',$cn);
if($_POST && isset($_GET['ID'])){    aggiorna_record();}elseif(isset($_GET['ID'])){    mostra_record();}else    mostra_lista();
function mostra_lista(){    if(isset($_GET['msg']))        echo '<b>'.htmlentities($_GET['msg']).'</b><br /><br />';
    $query = "SELECT ID FROM tabella";
    $result = mysql_query($query);
    if (!$result) {        die("Errore nella query $query: " . mysql_error());    }
    echo '    <table border="1">        <tr>            <th>ID</th>            <th>&nbsp;</th>        </tr>';
    while ($row = mysql_fetch_assoc($result))    {        $ID = htmlspecialchars($row['ID']);
                $link = $_SERVER['PHP_SELF'] . '?ID=' . $row['ID'];echo "<tr>                <td>$ID</td>                <td><a href=\"$link\">VIEW</a></td>            </tr>";                }echo "</table>";
    mysql_free_result($result);
    mysql_close();}
function aggiorna_record(){            //funziona}
function mostra_record(){    if(isset($_GET['msg']))        echo '<b>'.htmlentities($_GET['msg']).'</b><br /><br />';
    $ID = intval($_GET['ID']);
    $query = "SELECT tabella1.cyl,                     tabella2.operating_pressure                                FROM     tabella1,                     tabella2,                    tabella,                    tabella3                   WHERE    tabella.ID = $ID AND                       tabella.FkEngine=tabella3.ID2 AND                     tabella3.Fkcyl=tabella1.id AND                     tabella3.Fkoperating_pressure=tabella2.id";
    $result = mysql_query($query);
    if (!$result) {        die("Errore nella query $query: " . mysql_error());    }
    if(mysql_num_rows($result) != 1) {        die("l'ID passato via GET è errato");    }
    list($cyl,        $operating_pressure) = mysql_fetch_row($result);
        $cyl= htmlspecialchars($cyl);        $operating_pressure= htmlspecialchars($operating_pressure);            mysql_close();    ?>    <form name="form_registrazione" method="post" action="">      <table width=”200″ border=”0″>      <tr>        <td>FkCyl:</td>        <td><?php     include ("config.php");         $DBName="db";
    mysql_select_db("$DBName") or die("Impossibile connettersi al database $DBName");
    //table tabella1    $sql ="SELECT id FROM tabella2 where cyl='$cyl'";    $r= mysql_query($sql);    $v= mysql_fetch_array($r);    echo "<div id=styled-select> <select name='cyl'>";     echo "<option value = ".$v['id']." >$cyl</option>";        $sqlquery ="SELECT id,cyl FROM tabella1";    $result = mysql_query($sqlquery);        if (!$sqlquery) {           exit ('<p> Errore mentre recuperavo i dati' . mysql_error() . '</p>');                }                     while ($value= mysql_fetch_array($result))     {     echo "<option value = ".$value['id'].">".$value['cyl']."</option>";    }echo "</select> </div>";                ?> </td>      </tr>           </td>        <td>Operating pressure: </td>        <td><?php     $sql ="SELECT id FROM tabella2 where operating_pressure='$operating_pressure'";    $r= mysql_query($sql);    $v= mysql_fetch_array($r);    echo "<div id=styled-select><select name='operating_pressure'>";     echo "<option value = ".$v['id']." >$operating_pressure</option>";        $sqlquery ="SELECT id,operating_pressure FROM tabella2";    $result = mysql_query($sqlquery);    if (!$sqlquery) {           exit ('<p> Errore mentre recuperavo i dati' . mysql_error() . '</p>');                }     while ($value= mysql_fetch_array($result))     {     echo "<option value = ".$value['id'].">".$value['operating_pressure']."</option>";   }echo "</select> </div>";        ?></td>        </tr>      </table>     <br> <br>       <p>        <input name="invia" type="submit" value="Save" />      </p>    </form>
<?php}mysql_close();?>

Non mi funziona questa parte:

//table tabella1    $sql ="SELECT id FROM tabella2 where cyl='$cyl'";    $r= mysql_query($sql);    $v= mysql_fetch_array($r);    echo "<div id=styled-select> <select name='cyl'>";     echo "<option value = ".$v['id']." >$cyl</option>";        $sqlquery ="SELECT id,cyl FROM tabella1";    $result = mysql_query($sqlquery);        if (!$sqlquery) {           exit ('<p> Errore mentre recuperavo i dati' . mysql_error() . '</p>');                }                     while ($value= mysql_fetch_array($result))     {     echo "<option value = ".$value['id'].">".$value['cyl']."</option>";    }echo "</select> </div>";                ?> </td>      </tr>           </td>        <td>Operating pressure: </td>        <td><?php     $sql ="SELECT id FROM tabella2 where operating_pressure='$operating_pressure'";    $r= mysql_query($sql);    $v= mysql_fetch_array($r);    echo "<div id=styled-select><select name='operating_pressure'>";     echo "<option value = ".$v['id']." >$operating_pressure</option>";        $sqlquery ="SELECT id,operating_pressure FROM tabella2";    $result = mysql_query($sqlquery);    if (!$sqlquery) {           exit ('<p> Errore mentre recuperavo i dati' . mysql_error() . '</p>');                }     while ($value= mysql_fetch_array($result))     {     echo "<option value = ".$value['id'].">".$value['operating_pressure']."</option>";   }echo "</select> </div>";        ?></td>        </tr>

in particolare queste due query:

$sql ="SELECT id FROM tabella2 where cyl='$cyl'";
$sql ="SELECT id FROM tabella2 where operating_pressure='$operating_pressure'"; 

non mi trova i valori di $cyl e $operating_pressure. Ho provato a stampare i valori di queste variabili e sono giusti. Quando faccio questo confronto cyl='$cyl'" non trova il record, la stessa cosa succede per operating_pressure='$operating_pressure'.

Grazie mille a tutti