php+ajax无刷新实现省、地、市三级联动

html>
head>
meta http-equiv="Content-Type" c />
script type="text/javascript">
var xmlHttp;
var requestType="";
function createXMLHttpRequest()
{
if(window.ActiveXObject)
{
  xmlHttp=new ActiveXObject("Microsoft.XMLHTTP");
}
else if(window.XMLHttpRequest)
{
  xmlHttp=new XMLHttpRequest();
}
}
function queryCity(citycode){
createXMLHttpRequest();
type="city";
var url="data.php?provincecode="+citycode;
xmlHttp.open("GET",url,true);
xmlHttp.onreadystatechange=handleStateChange;
xmlHttp.send(null);
}
function queryArea(citycode){
createXMLHttpRequest();
type="area";
var url="data.php?citycode="+citycode;
xmlHttp.open("GET",url,true);
xmlHttp.onreadystatechange=handleStateChange;
xmlHttp.send(null);
}
function handleStateChange(){
if(xmlHttp.readystate==4){
  if(xmlHttp.status==200){
   if(type=="city"){
    showcity();
   }else if(type="area"){
    showarea();
   }
  }
}
}
function showcity(){
document.getElementById("city").innerHTML=xmlHttp.responseText;
document.getElementById("area").innerHTML="";
}
function showarea(){
document.getElementById("area").innerHTML=xmlHttp.responseText;
}




$conn=mysql_connect("localhost","root","2328725");
mysql_select_db("novel");
mysql_query("set names 'utf8'");
$sql="select * from province";
$result=mysql_query($sql);
echo "\n";
echo "\n";
echo "请选择省份\n";
while($row=mysql_fetch_row($result)){
  echo "$row[2]\n";
}
echo "\n";
echo "\n";
echo "\n";
echo "\n";
?>