Checking XML using Google Maps API

I have been playing around with Google Maps API for the past couple of days. I got up to the point where I'm stuck because of my lack of PHP skills. After running the PHP code below, the XML returned is:

<?xml version="1.0"?>
<markers/>

The link I'm using is: http://www.icliqz.com/Dev/phpsqlsearch_genxml_php.php?latitude=41.782321&longitude=-72.612031&radius=50

The code I'm playing around with is from: http://code.google.com/apis/maps/articles/phpsqlsearch.html

I'm using Dreamweaver to work on this project. If there's a good way to debug through PHP code, I'd really appreciate it. I tried googling it up, but I'm not sure what is best for a PHP newbie. I checked that the radius of the records I have in my database. They are all within 50 miles of the coordinates I'm testing with.

The PHP code is:

<?php
require("phpsqlsearch_dbinfo.php");

// Start XML file, create parent node
$doc = new DOMDocument("1.0");
$node = $doc->createElement("markers");
$parnode = $doc->appendChild($node);

// Opens a connection to a mySQL server
$connection=mysql_connect (localhost, $username, $password);
if (!$connection) {
  die('Not connected : ' . mysql_error());
}

// Set the active mySQL database
$db_selected = mysql_select_db($database, $connection);
if (!$db_selected) {
  die ('Can\'t use db : ' . mysql_error());
}

/开发者_运维百科/ Select all the rows in the markers table
$query = "SELECT user, latitude, longitude, ( 3959 * acos( cos( radians('%s') ) * cos( radians( latitude ) ) * cos( radians( longitude ) - radians('%s') ) + sin( radians('%s') ) * sin( radians( latitude ) ) ) ) AS distance FROM tbl_UserLatLng HAVING distance < '%s' ORDER BY distance LIMIT 0 , 20";
$result = mysql_query($query);
if (!$result) {
  die('Invalid query: ' . mysql_error());
}

header("Content-type: text/xml");

// Iterate through the rows, adding XML nodes for each
while ($row = @mysql_fetch_assoc($result)){
  // ADD TO XML DOCUMENT NODE
  $node = $doc->createElement("marker");
  $newnode = $parnode->appendChild($node);

  $newnode->set_attribute("user", $row['user']);
  $newnode->set_attribute("latitude", $row['latitude']);
  $newnode->set_attribute("longitude", $row['longitude']);
  $newnode->set_Attribute("distance", $row['distance']);
}

echo $doc->saveXML();

?>

Thanks in advance!

Try running your query manually from the mysql shell to see what values are showing up for distance. It seems like you're not getting any results from the db.

SELECT user, latitude, longitude, 
    ( 3959 * acos( cos( radians('%s') ) * cos( radians( latitude ) ) * cos( radians( longitude ) - 
    radians('%s') ) + 
    sin( radians('%s') ) * sin( radians( latitude ) ) ) ) AS distance 
FROM tbl_UserLatLng