title: Ajax first call
body: <p>I have a script that process data with some ajax call, depending on the user clicks and changes the call is done once again(works fine).</p>
  
  <pre><code>$.ajax({
     type: "POST",
     url: "process_data.php",
     data: { action: "first_action",data:data},
     dataType: 'json',
     success:function(result){
         //process
     },
     error: function(XMLHttpRequest, textStatus, errorThrown) {
     }
   });
  </code></pre>
  
  <p>To save time I want to execute some queries in my <code>process_data.php</code> file only during the first ajax call and save them into variables so I dont have to execute the same queries in every call.
  How to catch ajax first call ?</p>