Retrieve Database Data (Ajax)

[Dysan]

Hi,

 

I am keen to study how Ajax is coded, could anybody give me some simple Ajax code to tear apart, that retrieves data from a database and displays it on the screen?

[priti]

well you can google a lot of tutorials . There is one on w3schools

 

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

[shankar23]

in Ajax only xmlHttp is main part...

 

It will be used everywhere if Ajax exists...

 

So just learn how to pass variable to PHP or any scripting languages...

 

It will be usefull for you in future..

 

[RichardRotterdam]

I use frameworks only these days for my ajax funtionality prototype and and mootools do a great job with this. It makes you able to write a few simple lines instead of using the usually long script.

 

for example instead of using this which is a pain to modify for starters and i know i have been there

var xmlHttp

function showCustomer(str)
{ 
xmlHttp=GetXmlHttpObject();
if (xmlHttp==null)
  {
  alert ("Your browser does not support AJAX!");
  return;
  } 
var url="getcustomer.asp";
url=url+"?q="+str;
url=url+"&sid="+Math.random();
xmlHttp.onreadystatechange=stateChanged;
xmlHttp.open("GET",url,true);
xmlHttp.send(null);
}

function stateChanged() 
{ 
if (xmlHttp.readyState==4)
{ 
document.getElementById("txtHint").innerHTML=xmlHttp.responseText;
}
}

function GetXmlHttpObject()
{
var xmlHttp=null;
try
  {
  // Firefox, Opera 8.0+, Safari
  xmlHttp=new XMLHttpRequest();
  }
catch (e)
  {
  // Internet Explorer
  try
    {
    xmlHttp=new ActiveXObject("Msxml2.XMLHTTP");
    }
  catch (e)
    {
    xmlHttp=new ActiveXObject("Microsoft.XMLHTTP");
    }
  }
return xmlHttp;
}

 

you can use this

//when the button start is clicked the ajax function will start
$('start').addEvent('click', function(e) {
e = new Event(e).stop();
       //the external page that will be loaded
var url = "http://demos.mootools.net/demos/Ajax/lipsum.html";

/**
 * The simple way for an Ajax request, use onRequest/onComplete/onFailure
 * to do add your own Ajax depended code.
 */
new Ajax(url, {
	method: 'get',
	update: $('log')//the element log that will be updated <div id="log"></div>
}).request();
});