[melky]

<script type="text/javascript" src="http://code.jquery.com/jquery.min.js"></script>
<script type="text/javascript">
$(document).ready(function() {
    $.getJSON('http://site.ru/mysql_test/mysql2.php?callback=?',
        function(data) {
            if (data)  {
                var cod = data.code;
                alert(cod);
                *!*alert(data.foo)*/!*
            }
        });
});
 </script>

echo $_GET['callback']."({code:$date*!*, foo : 'bar'*/!*})";