code: public function addPrivateChatUpdate ($msgid, Neuron_GameServer_Player $from, Neuron_GameServer_Player $target)
  	{
  		$msgid = intval ($msgid);
  
  		$db = Neuron_DB_Database::getInstance ();
  
  		$db->query
  		("
  			DELETE FROM
  				n_privatechat_updates
  			WHERE
  				pu_to = {$target->getId ()} AND
  				pu_from = {$from->getId ()}
  		");
  
  		return $db->query
  		("
  			INSERT INTO
  				n_privatechat_updates
  			SET
  				pu_from = {$from->getId ()},
  				pu_to = {$target->getId ()},
  				c_m_id = $msgid,
  				pu_date = NOW()
  		");
  	}
docs: CREATE TABLE  `n_privatechat_updates` (
  `pu_id` INT NOT NULL AUTO_INCREMENT PRIMARY KEY ,
  `pu_from` INT NOT NULL ,
  `pu_to` INT NOT NULL ,
  `pu_date` DATETIME NOT NULL
  ) ENGINE = INNODB