public function getFriendsData($uid)
{
$data = D()->table('`' . $this->tablePrefix . 'user_follow` AS a LEFT JOIN `' . $this->tablePrefix . 'user_follow` AS b ON a.uid = b.fid AND b.uid = a.fid')->field('a.fid')->where('a.uid = ' . $uid . ' AND b.uid IS NOT NULL')->findAll();
return $data;
}