<?php

$text = "labas tralala  asda code:8745 sfd  code:9454563  asda";

$pattern = '#code:(.*?) #si';

preg_match_all($pattern, $text, $matches);

foreach ($matches[1] as &$id) {

// select * from lenta where id=$id

$text = str_replace("code:".$id,"<a href='http://labas(".$id.")'>Nuoroda(".$id.")</a>",$text);

}

echo $text;

?>