Wie kann man AJAX verwenden, um die Länderliste in Abhängigkeit von der Länderliste aufzufüllen?

Question

Ich habe den Code unten, dass ein Zustand Dropdown-Liste ändern, wenn Sie die Länderliste ändern.
Wie kann ich erreichen, dass die Liste der Bundesländer NUR dann geändert wird, wenn die Länder-ID-Nummern 234 und 224 ausgewählt sind?
Wenn ein anderes Land ausgewählt wird, sollte es in dieses Texteingabefeld übertragen werden

<input type="text" name="othstate" value="" class="textBox">

Das Formular

<form method="post" name="form1">
<select style="background-color: #ffffa0" name="country" onchange="getState(this.value)">
<option>Select Country</option>
<option value="223">USA</option>
<option value="224">Canada</option>
<option value="225">England</option>
<option value="226">Ireland</option>
</select>

<select style="background-color: #ffffa0" name="state">
<option>Select Country First</option>
</select>

Das Javascript

<script>
function getState(countryId)
{
   var strURL="findState.php?country="+countryId;
   var req = getXMLHTTP();
   if (req)
   {
     req.onreadystatechange = function()
     {
      if (req.readyState == 4)
      {
     // only if "OK"
     if (req.status == 200)
         {
        document.getElementById('statediv').innerHTML=req.responseText;
     } else {
       alert("There was a problem while using XMLHTTP:\n" + req.statusText);
     }
       }
      }
   req.open("GET", strURL, true);
   req.send(null);
   }
}
</script>

Answer 1

////////////////// connection file con.php rishabh
<?php
ini_set('display_errors', 1);
ini_set('display_startup_errors', 1);
error_reporting(E_ALL);
         $dbhost = 'localhost';
         $dbuser = 'root';
         $dbpass = '';
         $conn = mysql_connect($dbhost, $dbuser, $dbpass);
         if(! $conn ) {
            die('Could not connect: ' . mysql_error());
         }
         mysql_select_db( 'testajax' );
?>

/////////////////////////// index.php rishabh
<script src="https://code.jquery.com/jquery-1.12.4.min.js"></script>
<?php 
include('con.php');
?>
<form>
<div class="frmDronpDown">
    <div class="row">
        <table><tr><td><label>Country:</label><br/>
        <select name="country" id="country" data-name="country" class="demoInputBox" onChange="getCountry(this.value);">
        <option value="">Select Country</option>
        <?php
         $sql = mysql_query("SELECT distinct country FROM statecont ");
     while($result=mysql_fetch_array($sql)){
        ?>
        <option value="<?php echo $result['country']; ?>"><?php echo $result['country']; ?></option>
        <?php
        }
        ?>
        </select> </td>
             <td>
<label>Phone:</label><br/>
        <select name="phone" id="phone" data-name="phone" class="demoInputBox" onChange="getPhone(this.value);">
        <option value="">Select Country</option>
        <?php
         $sql = mysql_query("SELECT distinct phone FROM statecont ");
     while($result=mysql_fetch_array($sql)){
        ?>
        <option value="<?php echo $result['phone']; ?>"><?php echo $result['phone']; ?></option>
        <?php
        }
        ?>
        </select> 
</td></tr></table>
    </div>
    <div id="state-list"></div>
</div>
</form>
<script>
function getCountry(val) {
        var dataname = $('#country').attr('data-name');

        console.log(dataname);
    $.ajax({
    type: "POST",
    url: "data.php",
        data: {
                value_name: val,
                colomn_name: dataname
                },
    success: function (data){
        $("#state-list").html(data);
    }
    });
}

function getPhone(val) {
        var dataname = $('#phone').attr('data-name');

    console.log(dataname);
    $.ajax({
    type: "POST",
    url: "data.php",
        data: {
                 value_name: val,
                colomn_name: dataname
                },
    success: function (data){
        $("#state-list").html(data);
    }
    });
}
</script>

// ////////////////////data file data.php rishabh
<?php 
$val = $_POST["value_name"]; 
$colomn = $_POST["colomn_name"]; 
include('con.php');
$sql_aa = mysql_query("SELECT * FROM statecont where ".$colomn."='$val'"); ?>
  <table>
<tr><td>State</td><td>Countery</td></tr>
<?php while($result_aa=mysql_fetch_array($sql_aa)){ ?>
<tr><td><?php echo $result_aa['state']; ?></td><td><?php echo $result_aa['country']; ?></td></tr>
<?php } ?>
</table>