<?php
$users = $db->query("SELECT * FROM users")->results();
if(!empty($_POST['fname'])){
      foreach ($_POST['fname'] as $key=>$value){
        $db->update('users',$key,['fname'=>$value]);
}
Redirect::to('index.php?err=Updated!');
}
?>

<form class="" action="index.php" method="post">
    <?php foreach($users as $u){ ?>
    <input type="text" name="fname[<?=$u->id?>]" value="<?=$u->fname?>">
<?php } ?>
    <input type="submit" name="submit" value="submit">
</form>