Date not inserting in mysql_query insert
===

I am trying to insert a row into database. All entries insert correctly, however the date is inserted as: 

    0000-00-00

I have tried formatting the date manually:

        	$updated = $a["updated"][0];
			
			$updated = explode(" ", $updated);
			$updated[1] = explode("/", $updated[1]);
			
			$y = date('Y');
			$m = $updated[1][1];
			$d = $updated[1][0];
			
			$updated = $y . '-' . $m . '-' . $d;
			
			$updated = strtotime( $updated );
			echo '<pre>'. $updated .'</pre>';
			$upd = date('Y-m-d', $updated);
			
			$a["updated"][0] = $updated;			
			echo '<pre>'. $upd .'</pre>';

This is the output of the var_dump($a):

    1342134000

    2012-07-13

    array(3) {
      ["metal"]=>
      string(6) "Silver"
      ["am"]=>
      array(3) {
        [0]=>
        string(7) "2748.00"
        [1]=>
        string(8) "1779.220"
        [2]=>
        string(8) "2253.200"
      }
      ["updated"]=>
      array(1) {
        [0]=>
        int(1342134000)
      }
    }


I have also tried using mysql_date_format but the row is not inserted at all:

    $updated = mysql_date_format($updated);

This is my insert query

    mysql_query("INSERT INTO LondonFixes VALUES(null,'" . $a["metal"] . "','AM'," . $a["am"][1] . "," . $a["am"][0] . "," . $a["am"][2] . "," . $a["updated"][0] . ", null)");

This is my table structure

        CREATE TABLE IF NOT EXISTS `LondonFixes` (
      `id` int(11) NOT NULL AUTO_INCREMENT,
      `Metal` varchar(10) CHARACTER SET latin1 COLLATE latin1_general_ci NOT NULL,
      `AmPm` varchar(2) CHARACTER SET latin1 COLLATE latin1_general_ci NOT NULL,
      `GBP` decimal(10,5) NOT NULL,
      `USD` decimal(10,5) NOT NULL,
      `EUR` decimal(10,5) NOT NULL,
      `Updated` date NOT NULL,
      `TimeStamp` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
      PRIMARY KEY (`id`),
      UNIQUE KEY `Entry` (`Metal`,`AmPm`,`Updated`)
    ) ENGINE=MyISAM  DEFAULT CHARSET=latin1 AUTO_INCREMENT=229 ;

There is probably a very simple solution to this, but go easy on me please!