Untitled

<html>
<head>
<?php
    $lettera = $_POST["lettera"];
    if(isset($lettera)){
        include("connettoreDB.php");
        $lettera = strtoupper($lettera);
        $query = "SELECT CONCAT(s.Nome,' ',s.Cognome) as nominativo FROM `Studenti` as s, `Voti` as v WHERE s.Cognome LIKE '".$lettera."%' AND s.ID = v.ID_Studente AND v.Voto > 6 GROUP BY s.Cognome";
        $result = mysqli_query($link, $query);
        while($row = mysqli_fetch_array($result)){
            print($row["nominativo"]);
            print("<br>");
        }
    }
?>
</head>
<body>
<form name = "f1" method = "POST" action = "">
<select name = "lettera">
<?php
    // dal 65 al 90
    for($c = 65; $c <= 90; $c++){
        print("<option value='".strtolower(chr($c))."'>".chr($c)."</option>");
    }
?>
</select>
<input type = "submit" value = "invio">
</form>
</body>
</html>