http.open POST

http://www.w3schools.com/ajax/ajax_xmlhttprequest_send.asp

if (window.XMLHttpRequest)// code for IE7+, Firefox, Chrome, Opera, Safari

xmlhttp=new XMLHttpRequest();

else// code for IE6, IE5

xmlhttp=new ActiveXObject("Microsoft.XMLHTTP");

xmlhttp.open("POST", url, true);

xmlhttp.setRequestHeader("Content-type", "application/x-www-form-urlencoded");

xmlhttp.setRequestHeader("Content-length", params.length);

xmlhttp.setRequestHeader("Connection", "close");

xmlhttp.onreadystatechange=function(){

if (xmlhttp.readyState==4 && xmlhttp.status==200)

sql.innerHTML=xmlhttp.responseText;

}

xmlhttp.send(params);