Select Relasi PHP

<select name="id_customer" id="id_customer" class="form-control" onChange="showCustomer(this.value)">

  <?php

   echo"<option value='$id_customer' ";  echo"> $id_customer</option>";

  $s="select * from `tb_customer`";

$q=getData($conn,$s);

foreach($q as $d){

$id_customer0=$d["id_customer"];

$nama_customer=$d["nama_customer"];

echo"<option value='$id_customer0' ";if($id_customer0==$id_customer){echo"selected";} echo"> $nama_customer ($id_customer0)  </option>";

}

?>

</select>