Андрей

$data = "Яблоко - это фрукт. Слива фиолетовая.";
preg_match_all("~(?:яблоко|слива|груша)~ui", $data, $match);
var_dump($match);

SELECT * FROM  `users`
WHERE `ip` IN (select `ip` FROM `users_base` WHERE `user_id` = 'blahblahblah');

create table `user_tmp` (ip VARCHAR(32));
insert INTO `user_tmp` (select `ip` from `users` WHERE `user_id` = 'blahblahblah');
select * from  `users` WHERE `ip` IN (select `ip` FROM `user_tmp`);