Google Maps API javascript var

<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>Untitled Document</title>
<script type="text/javascript" src="http://maps.googleapis.com/maps/api/js?sensor=false"></script>
<style>
#map-canvas {height:500px;width:500px;}
</style>
</head>
<body onload="initialize()">
<?php
include "db.php";

$query = mysql_query("SELECT latitude, longitude FROM tbl_users WHERE username='Admin'") or die(mysql_error());

while($row = mysql_fetch_array($query))
{
  $lat = $row['latitude'];
  $long = $row['longitude'];
}
?>
<div id="map-canvas"></div>
<div>
<b>Start: </b>
<!--<b>Home:</b><input type="text" size="2" name="home" value="" /> -->
<select id="start" onchange="calcRoute();">
  <option value="">Home</option>
  <option value="chicago, il">Chicago</option>
  <option value="st louis, mo">St Louis</option>
  <option value="joplin, mo">Joplin, MO</option>
  <option value="oklahoma city, ok">Oklahoma City</option>
  <option value="amarillo, tx">Amarillo</option>
  <option value="gallup, nm">Gallup, NM</option>
  <option value="flagstaff, az">Flagstaff, AZ</option>
  <option value="winona, az">Winona</option>
  <option value="kingman, az">Kingman</option>
  <option value="barstow, ca">Barstow</option>
  <option value="san bernardino, ca">San Bernardino</option>
</select>
<b>End: </b>
<select id="end" onchange="calcRoute();">
  <option value="chicago, il">Chicago</option>
  <option value="st louis, mo">St Louis</option>
  <option value="joplin, mo">Joplin, MO</option>
  <option value="oklahoma city, ok">Oklahoma City</option>
  <option value="amarillo, tx">Amarillo</option>
  <option value="gallup, nm">Gallup, NM</option>
  <option value="flagstaff, az">Flagstaff, AZ</option>
  <option value="winona, az">Winona</option>
  <option value="kingman, az">Kingman</option>
  <option value="barstow, ca">Barstow</option>
  <option value="san bernardino, ca">San Bernardino</option>
  <option value="manchester, uk">Manchester</option>
</select>
</div>
<input type="text" value="<?php echo $lat; ?>" id="lat" name="lat" />
<input type="text" value="<?php echo $long; ?>" id="long" name="long" />
 <script>
  var directionDisplay;
  var directionsService = new google.maps.DirectionsService();
  var map;
  var lat = document.getElementById('lat').value;
  var long = document.getElementById('long').value;

  function initialize() {
    directionsDisplay = new google.maps.DirectionsRenderer();
    var chicago = new google.maps.LatLng(41.850033, -87.6500523);
    var home = new google.maps.LatLng(lat, long); //this is for the value in the database
    var mapOptions = {
      zoom:7,
      mapTypeId: google.maps.MapTypeId.ROADMAP,
      center: home
    }
    map = new google.maps.Map(document.getElementById('map-canvas'), mapOptions);
    directionsDisplay.setMap(map);
  }

  function calcRoute() {
    var start = document.getElementById('start').value;
    var end = document.getElementById('end').value;
    var request = {
        origin:start,
        destination:end,
        travelMode: google.maps.DirectionsTravelMode.DRIVING
    };
    directionsService.route(request, function(response, status) {
      if (status == google.maps.DirectionsStatus.OK) {
        directionsDisplay.setDirections(response);
      }
    });
  }
</script>
</body>
</html>