jQuery AJAX - čtení obsahu volaného PHP skriptu

$(document).ready(function($){
$("#ulozit").click(function() {

    var url = "zpracuj_data.php"; // the script where you handle the form input.

    $.ajax({
           type: "POST",
           url: url,
           data: $("#id_formulare").serialize(), // serializes the form's elements.
           success: function(data)
           {
               alert('Zpracováno'); // show response from the php script.
           }
         });

    return false; // avoid to execute the actual submit of the form.
});
     }

jQuery.ajax({
    url: "skript.php",
    type: "POST",
    vracenaData: "ukazka=1",
    cache: false,
    dataType: "xml",
    success: function(vracenaData) {
         alert(vracenaData);
    }
});