Affichage

<select id="mySelect" onchange="myFunction()">
  <option value=""> إselect filiere</option> 
               <?php
                include 'conexion.php';
                $sql=$conn->query("SELECT * FROM filiere");
                $sql->setFetchMode(pdo::FETCH_OBJ);
                
                while($po= $sql->fetch()){
                         $po->fildesc;
                ?> 
                <option value="<?php echo  $po->fildesc;  ?>"> <?php echo  $po->fildesc; ?></option>
                <?php
                 }

                ?>
          </select>


<p id="demo">

    <select>
      <option value="">select matiere</option>

    </select>
  </form>
</p>

<script>
function myFunction() {
    var x = document.getElementById("mySelect").value;
    document.getElementById("demo").innerHTML = "You selected: " + x;
}
</script>