Question

I have a mysql database that stores data such as usernames. I have a PHP file called result which retrieves the results from the database and encodes them into a JSON string. I then want the same PHP file to output the results without a page reload (via ajax). Effectively I want the same page to get the JSON string as a HTTP request, how do I go about this

this is results.php so far

            <?php

        $link = mysql_connect('', '', '');
        if (!$link) {
            die('Could not connect: ' . mysql_error());
        }

        $db_selected = mysql_select_db('test', $link);
        if (!$db_selected) {
            die ('Can\'t use test : ' . mysql_error());
        }

        $result = mysql_query("SELECT user_name FROM users");
        if (!$result) {
            die('Invalid query: ' . mysql_error());
        }


        $names = array();

        while ($row = mysql_fetch_assoc($result)) {

            foreach ($row as $key => $val) {

                $names[][$key] = $val;
            }
        }

        if ($_GET['myvar'] == "done")
        {
            $ennames = json_encode($names);
            echo $ennames;
            exit();
        }




        ?>
         <script src="jquery-1.7.1.min.js">

         function getJSON()
         {
            $.getJSON("results.php", { myvar: "done" }, function(data) {
               var namesHTML = "";

               $.each(data, function(key, val) {
                   namesHTML = namesHTML + val + "<br/>";
                 });

               $("#divForNames").html(namesHTML);
            });
            setTimeOut(getJSON, 5000); //the 5000 here means 5 seconds
         }
        </script>

         <div id="divForNames">

         </div>

Answer 1

The only adjustment that your PHP will need for this is to add an if statement immediately after the assignment of $ennames:

if ($_GET['myvar'] == "specific-value-that-you-choose")
{
   echo $ennames;
   exit();
}

For the polling, you will need to do some kind of client-side script – most likely javascript, and most easily written in jQuery. Look into the .getJSON() jQuery function and the setTimeOut() to create logic to do this polling. It will probably look something like this:

function getJSON()
{
   $.getJSON("result.php", { myvar: "specific-value-that-you-choose" }, function(data) {
      var namesHTML = "";

      $.each(data, function(key, val) {
          namesHTML = namesHTML + val + "<br/>";
        });

      $("#divForNames").html(namesHTML);
   });
   setTimeOut(getJSON, 5000); //the 5000 here means 5 seconds
}

Then somewhere in the HTML for the non-JSON page, you need to include a <div> with the id set to match the one you using inside the $.getJSON() function (in this case, I’d need an empty <div id="divForNames"> but you can change the names to fit your preferences.