Q:

how to check which button is clicked in php file with ajax call

I have a form post.php where the user inputs data and receivepost.php where the data entered is transferred through ajax post. I want to achieve the following in the receivepost.php :
        if(button save is pressed) {
            save to database

        }else if(button retrieve is pressed) {
          retrieve from database
}

I tried using isset($_POST['submit']) on the reveivepost.php but it does not detect the button which is pressed. The ajax post is working and all the data is available on the receivepost page. I have another solution that is to create 2 different php files and run them according to the button pressed but i think there is a better solution to it.
Here is my ajax call :
$("document").ready(function () {

  $("#submit").click(function () {

        var xmlhttp;

        // test browsers
        if(window.XMLHttpRequest) {

          xmlhttp = new XMLHttpRequest();

        }else {
          xmlhttp = new ActiveXObject("Microsoft.XMLHTTP");
        }

        // get the values of textboxes
        var desc_text = $("#desc").val();
        var speed_text = $("#speed").val();
        var tarea_text = $("#tarea").val();

        // variable to hold value of textboxes
        var content = "desc=" + desc_text + "&speed=" + speed_text + "&tarea=" + tarea_text;

        // open the request
        xmlhttp.open("POST", "receivepost.php", true);

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

        // check xmlhttp state and status and display text in div
        xmlhttp.onreadystatechange = function() {
          if (xmlhttp.readyState == 4 && xmlhttp.status == 200) {

           document.getElementById('para').innerHTML = xmlhttp.responseText;
          }

        }
        // send the content of the textboxes
        xmlhttp.send(content);

      });
   });

Here is my post.php form : 
<form id="myform">

    <label for="description">Description:</label>
    <input type="text" id="desc" name="desc" /><br/>

    <label for="speed">Speed: </label>
    <input type="text" id="speed" name="speed" /><br/>

    <textarea id="tarea" cols="10" rows="10" name="tarea"></textarea><br/>

    <input type="button" id="submit" name = "submit" value="Save">
    <input type="button" id="retrieve" name="retrieve"  value="Retrieve">

 </form>
<div id="para"></div>

A:

Try to add to the content an extra parameter called button-pressed which you can later use in receivepost.php as below:
if($_POST['button-pressed']=="save"){  
    //savetodb code  
}
else if($_POST['button-pressed']=="retrieve"){  
    //retreivefromdb code  
}

Perhaps you have two JavaScript functions, one on each button:
$("#submit").click(function () {
    var content = "button-pressed=save" + "&desc=" + desc_text + "&speed=" + speed_text + "&tarea=" + tarea_text;

$("#retrieve").click(function () {
    var content = "button-pressed=retrieve" + "&desc=" + desc_text + "&speed=" + speed_text + "&tarea=" + tarea_text;

Hope this helps?

