$ideas = $this->db->select('*, user.id as user_id')->from('napad')
    ->innerJoin('user')->on('napad.id_user = user.id');


 //latte

{foreach $ideas as $idea}
<tr>
  <td>ID uživatele {$idea->user_id}</td>
  <td>Nápad {$idea->nazev}</td>
</tr>