Просмотр поста

if (preg_match('~@([\w]+)~iu', $url, $match)) {
    $query = mysql_query("
        SELECT * FROM `users` 
        WHERE `name` = '". mysql_real_escape_string($match[1]) ."'
    ");

    $ud_st = mysql_fetch_assoc($query);

    if (!empty($ud_st['id'])) {
        $repl = '<a href="http://'. $_SERVER['HTTP_HOST'] .
            '/users/profile.php?user='. $ud_st['id'] .'">'. 
            $match[0] .'</a>';
        
        echo str_replace($match[0], $repl, $url);
    } else {
        echo str_replace($match[0], $match[1], $url);
    }
} else {
    echo $url;
}