Database worlddata

Table Country

idCountry
nameCountry

Table State

idCountry
idState
nameState

Table City

idCountry
idState
idCity
nameCity

class DBController  {

private $host = "localhost";
private $user = "USERNAME";
private $password = "PASSWORD";
private $database = "worlddata";
private $conn;

function __construct() {
    $this->conn = $this->connectDB();
}

function connectDB() {
    $conn = mysqli_connect($this->host,$this->user,$this->password,$this->database);
    mysqli_set_charset($conn,"utf8");
    return $conn;
}

function runQuery($query) {
    $result = mysqli_query($this->conn,$query);
    while($row=mysqli_fetch_assoc($result)) {
        $resultset[] = $row;
    }
    if(!empty($resultset))
        return $resultset;
}

function numRows($query) {
    $result  = mysqli_query($this->conn,$query);
    $rowcount = mysqli_num_rows($result);
    return $rowcount;
}

              }

<script src="jquery-3.2.1.min.js" type="text/javascript"></script>
 <script>
 function getState(val) {
   $.ajax({
   type: "POST",
   url: "getState.php",
   data:'idCountry='+val,
   success: function(data){
    $("#state-list").html(data);
    getCity();
   }
   });
 }


function getCity(val) {
$.ajax({
type: "POST",
url: "getCity.php",
data:'idState='+val,
success: function(data){
    $("#city-list").html(data);

  }
   });
 }
 </script>
<?php
 require_once("dbcontroller.php");
 $db_handle = new DBController();
 $query ="SELECT * FROM Country";
$results = $db_handle->runQuery($query);
?>
<?php
 echo"<ul>";
foreach($results as $country) {

 <li >
      <a href="#" name="country" id="country-list" class="demoInputBox" onclick="getState(<?php echo $country["idCountry"]; ?>);" >
<?php echo $country["namaCountry"]; ?>
</a>

<div id='state-list'></div>

  </li>

  <?php
}
  echo"</ul>"
  ?>

<?php
    require_once ("dbcontroller.php");
   $db_handle = new DBController();
   if (! empty($_POST["idnegara"])) {
   $query = "SELECT * FROM State WHERE idCountry = '" . $_POST["idCountry"] . "'";
   $results = $db_handle->runQuery($query);
   ?>

   <?php
      foreach ($results as $state) {

    ?>
   <li>
  <a href="#" name="state" id="state-list" class="demoInputBox" onclick="getCity(<?php echo $state["idState"]; ?>);">


  <?php echo $state["nameState"]; ?>
 </a>

     <div id='city-list'></div>


 <?php
  }
 }
   ?>

 <ul>

<ul>
   <?php
      error_reporting(0);
      require_once ("dbcontroller.php");
      $db_handle = new DBController();
   if (! empty($_POST["idprofinsi"])) {
   $query = "SELECT * FROM City WHERE idState = '" . $_POST["idState"] . "'
   order by nameCity asc";
  $results = $db_handle->runQuery($query);
  ?>

  <?php
      foreach ($results as $city) {
    ?>
      <li>
       <a href="#" name="city" id="city-list" class="demoInputBox" onclick="getCity(<?php echo $city["idState"]; ?>);">

   <div id='city-list'><?php echo $city["namecity"]; ?></div>
</li>
</a>

  <?php
   }
}
?>
</ul>