<textarea class="input"  style="width:100%;font-size:12pt;font-family: ArialMT, Verdana;font-weight: bold;height:100px;color:black" name="adresse" readonly="readonly" id="street"></textarea>
        <input style="width:130px;text-align: left" class="input" type="text" name="kundennr" id="kundennr" value="10000">



<?php
$sql = "SELECT * FROM `kunde` ORDER BY `kundennummer` ASC";
 foreach ($dbh->query($sql) as $nav) {
$address = $nav['adresse'];
$name = $nav['kundennummer'];
 echo " <a>$address</a>
<a> |  Kundennr: </a><a href='#' onclick='changeit(this);'>$name</a><br>";
        }
    ?>
</div>
    </div>
    <script>function changeit(el) {
        var inhalt = el.text;
        var db_address = '<?php echo $address; ?>';
        document.getElementById('kundennr').value=inhalt;
        document.getElementById('street').value =db_address;
    }
    </script>