public function add($content)
{
$time = intval(RECORD_DAYS_MESSAGE) * 24;
$time = '-' . strval($time) . ' hour';
$time = date('Y-m-d', strtotime($time, time()));
$sql = "DELETE FROM `wx_message` WHERE `time` <= '{$time}'";
$this->delete($sql);
$content = str_replace("'", "''", $content);
$sql = "INSERT INTO `wx_message` (`openid`, `content`, `type`) VALUES ('{$this->fromUserName}','{$content}', 'rcv')";
$this->insert($sql);
include_once dirname(__FILE__) . '/user/info.php';
$info = new UserInfo($this->fromUserName);
$info->load();
}