untuk get nya

   <?php
    $con = mysql_connect("localhost","root","");
    mysql_select_db('db_umroh');
    $user=$_SESSION['login_user'];
    $key=substr($user,-4);

    $sql = "SELECT * FROM tabel_cabang WHERE id_cabang like '$key%'";
    $json = array();
    $query = mysql_query($sql);
    while($data = mysql_fetch_array($query)){
    //sesuaikan dengan struktur tabelmu
    $json[] = array(
        'label' => $data['id_cabang'],
        'value' => $data['id_cabang'],
        'nama' => $data['kota_cabang']
    );
    }
    header("Content-Type: application/json");
    echo json_encode($json);
    ?>

untuk nampilinnya

<script type="text/javascript">

//tambahkan auto complete
$('#id_cabang').autocomplete({
source: "get_data.php",
minLength: 40,
select: function( event, ui ) {
$('#txtNm').val(ui.item.nama);
}
});
});
</script>


    
<tr>    
    <td height="36">Cabang Kota</td>
    <td><input name="txtNm" type="text"  id="txtNm" /></td>
 
      </tr>

Masalahnya gak muncul2 itu knp yah gan ..mohon bantuannya