php - Updating City List After State Selection -

so trying have website update state , city lists server.

my code states seems work fine, problem have updating city list. adapted answer here earlier, , doesn't seem work, although fault.

here state php code.

<?php      $con= mysqli_connect($host, $user, $pass, $database);     if($debug){         echo $host,$user,$pass,$database;      }     // check connection     if (mysqli_connect_errno())     {         echo "failed connect mysql: " . mysqli_connect_error();     }     $states = '';     $resultstate = mysqli_query($con,"select distinct state citiesstates");      while($row = mysqli_fetch_array($resultstate))      {     if($debug){         echo $row['state'];      }         $states .="<option>" . $row['state'] . "</option>";      }     $statesdrop="         <p><label>states</label></p>         <select name='states' id='states' onchange='getcity(this.value))'>             " . $states . "         </select>";     echo $statesdrop;     mysqli_close($con);  ?> 

so on selection should call function.

<script type="text/javascript">  function getcity(stateid) {   var strurl="findcity.php?state="+stateid;   var req = getxmlhttp();   if (req)   {    req.onreadystatechange = function()    {      if (req.readystate == 4) // if "ok"      {        if (req.status == 200)        {          document.getelementbyid('citydiv').innerhtml=req.responsetext;        } else {           alert("there problem while using xmlhttp:\n" + req.statustext);        }      }   }   req.open("get", strurl, true);   req.send(null);  } }  </script> 

which calls php file.

   $stateid=intval($_get['state']);    $con= mysqli_connect($host, $user, $pass, $database);      // check connection     if (mysqli_connect_errno())     {         echo "failed connect mysql: " . mysqli_connect_error();     }     $cities = '';     $resultcity = mysqli_query($con,"select city citiesstates state='$stateid'");      while($row = mysqli_fetch_array($resultcity))     {     if($debug){         echo $row['city'];      }         $cities .="<option>" . $row['city'] . "</option>";      }     $citiesdrop="         <p><label>cities</label></p>         <select name='cities' id='cities' onchange=''>             " . $cities . "         </select>";     echo $citiesdrop;     mysqli_close($con);     ?> 

additionally getxmlhttp() function, since seems problem

       function getxmlhttp() {        var x = false;        try {           x = new xmlhttprequest();        }catch(e) {          try {             x = new activexobject("microsoft.xmlhttp");          }catch(ex) {             try {                 req = new activexobject("msxml2.xmlhttp");             }             catch(e1) {                 x = false;             }          }       }       return x;     } 

i think due in findcity.php

$citiesdrop="     <p><label>states</label></p>     <select name='states' id='states' onchange='getcity(this.value))'>         " . $states . "     </select>"; 

it looks copied state php code, did not update correctly. php page sending req.status of 500, $states not defined. try updating -

$citiesdrop="     <p><label>cities</label></p>     <select name='cities' id='cities'>         " . $cities . "     </select>";