Populate list of options with Ajax - Replacing Prototype

Populate list of options with Ajax - Replacing Prototype

HI, I have a problem with a jQuery code.

Actually, I want to migrate from Propotype due to conflicts with other jQuery scripts.

I need display a list of options in a select from a previously option selected in another select.

I've tried several ways, but without success.

I added two fields to the users profile: City and Neighborhood. So, a form in the frontend to be able to search for users by city and neighborhood (of each city).

Here's my code:

The file  neighborhoodAjax.php

  2. <?php
  3. /*
  4.  This file is used to search the neighborhoods of the city selected in the first select and populate the list of neighborhoods of that city.
  5. */

  7. global $wpdb; // here's used for connect in DB and get the prefix of table

  9. if($_POST['meta_value']){

  11. $city_selected = $_POST['meta_value'];

  13. $neighborhood = "SELECT DISTINCT meta_value FROM $wpdb->usermeta WHERE meta_key = 'neighborhood_of_user' AND user_id IN (SELECT DISTINCT user_id FROM $wpdb->usermeta WHERE meta_key = 'city_of_user' AND meta_value = '".$city_selected."')";

  15. $neighborhood = sanitize_text_field($neighborhood);

  17. $neighborhood = mysql_query($neighborhood); ?>

  19.         <option value="" selected="selected">-- Select a Neighborhood --</option>

  21. <?php while($neighborhood = mysql_fetch_array($neighborhood)){ ?>

  23.         <option value="<?php echo $neighborhood['meta_value'] ?>" <?php if($_POST['select_neighborhood'] == $neighborhood['meta_value']) {?> selected="selected" <?Php } ?>> <?php echo $neighborhood['meta_value']?> </option>

  25. <?php }//Close the While

  27. }//Close the if
  28. ?>
The Script: 

  2. <script type="text/javascript">

  4. $(function() {

  6.   $("#city").bind("change", function() { // #city is ID of select

  8.      var meta_value = $("#city").val();
  9.         $.ajax({
  10.           url: "neighborhoodAjax.php",
  11.           type: "POST",
  12.           data: {id : meta_value},
  13.           dataType: "html"
  14.         });

  16.   });

  18. });

  20. </script>
The code will run in WordPress website, what I would like to know is where the error is. :(

Can anyone help me?

I am grateful.