How can I display sorted data from multiple tables ordered by date under dated headings?

I am working on a project management system and having to use multiple MySQL tables (messages, todo items, events, etc.) to pull and sort data from into a structured format using PHP.

The format should be similar to this

<p><b>Today</b></p>
<p>
  Todo Item, Item name, Item Description <br />
  Todo Item, Item name, Item Description <br />
  Message,   Message title               <br />
  Todo Item, Item name, Item Description <br />
  Todo Item, Item name, Item Description <br />
  Message,   Message title               <br />
</p>
<p><b>June 22, 2011</b></p>
<p>
  Todo Item, Item name, Item Description <br />
  Todo Item, Item name, Item Description <br />
  Todo Item, Item name, Item Description <br />
  Message,   Message title               &l开发者_运维知识库t;br />
  Todo Item, Item name, Item Description <br />
  Message,   Message title               <br />
</p>

Example MySQL tables are below:

CREATE TABLE `todo` (
  `id` int(12) NOT NULL auto_increment,
  `item` varchar(255) NOT NULL default '',
  `description` text NOT NULL,
  `created` int(12) NOT NULL default '0',
  PRIMARY KEY  (`id`)
) ENGINE=MyISAM;

INSERT INTO `todo` (`id`, `item`, `description`, `created`) VALUES
(1, 'test to-do list 1', 'this is simply a test 1', 1308847222),
(2, 'test to-do list 2', 'this is simply a test 2', 1308847318),
(3, 'test to-do list 3', 'this is simply a test 3', 1308847371),
(4, 'test to-do list 4', 'this is simply a test 4', 1306847441),
(5, 'test to-do list 5', 'this is simply a test 5', 1306848208);

CREATE TABLE `messages` (
  `id` int(12) NOT NULL auto_increment,
  `title` varchar(255) NOT NULL default '',
  `message` text NOT NULL,
  `created` int(12) NOT NULL default '0',
  PRIMARY KEY  (`id`)
) ENGINE=MyISAM;

INSERT INTO `messages` (`id`, `title`, `message`, `created`) VALUES
(1, 'test messages 1', 'this is simply a test 1', 1308847222),
(2, 'test messages 2', 'this is simply a test 2', 1308847318),
(3, 'test messages 3', 'this is simply a test 3', 1308847371),
(4, 'test messages 4', 'this is simply a test 4', 1306847441),
(5, 'test messages 5', 'this is simply a test 5', 1306848208);

What would be the best way to handle this efficiently?

---

A union query to retrieve all the items:

SELECT DATE(created) AS d, item, description, 'todo' AS src
FROM todo

UNION

SELECT DATE(created) AS d, title, message, 'messages' AS src
FROM messages

ORDER BY created

Then a simple state machine to handle output:

$prev_date = null;
$first = true;
while($row = mysql_fetch_assoc($query_results)) {
   if ($prev_date <> $row['d') {
        if (!$first) {
            echo "</p>';
        }
        echo "<p><b>{$row['d']</b></p><p>";
   }
   echo " ... rows stuff<br />";
}