getJSON function, return encoded array from multiple mysql queries

Question

I'm wondering if it is possible to combine many queries into one array and return it. The problem is that some of those queries already are arrays...here's what I mean:

JS:

function getNews() {
  $.getJSON(serviceURL + 'getmainnews.php', function(data) {
    $('#fnews li').remove();
    daily = data.items;
      $.each(daily, function(index, mnews) {
        //append the data to listview
      });
    });

Here is the php file with the queries:

<?php
  include 'connect_to_mysql.php';
  mysql_query("SET NAMES UTF8");
  $day = mysql_query("SELECT * FROM basket_news WHERE topic='daily' ORDER BY id DESC LIMIT 1");
  $daily = array();
  while ($r = mysql_fetch_assoc($day)){
    $daily[] = $r;
  }

  $sql = mysql_query("SELECT * FROM basket_news WHERE topic='' ORDER BY id DESC"); 
    $mainnews = array();
    while ($r = mysql_fetch_assoc($sql)){
      $mainnews[] = $r;
    }
?>

If I have more queries like this, how can I gather them together to be able to do something like:

echo json_encode(array("items" => $daily, "allitems" => $mainnews));

I understand that $daily has a LIMIT 1 with it, but others like $mainnews will be big arrays. How would I set up the PHP echo and get it back in JS? I guess if all else fails, I could do multiple ajax calls but that would be a waste...