autocomplete return id

<?php
$sql = mysql_query("SELECT id_jabatan, nm_jabatan FROM tbjabatan");
$options='';
while($j = mysql_fetch_array($sql)) {
  $options.= '{value:'.$j['id_jabatan'].',label:"'.$j['nm_jabatan'].'"},';
}
?>
<script>
$(function() {
  var availableJab = [<?php echo $options;?>];
  $("#nmjab").autocomplete({
    source: availableJab,
    focus: function(event, ui) {
      $("#nmjab").val(ui.item.label);
      return false;
    },
    select: function (event, ui) {
      $("#nmjab").val(ui.item.label);
      $("#idjab").val(ui.item.label);
      return false;
    }
  });

});
</script>
<label for="idjab">Jabatan</label> :
<!-- id jabatan -->
<input type="text" name="nmjab" id="nmjab" size="20px" class="inputxt" placeholder="Ketik Jabatan..." />
<input type="hidden" name="idjab" />