calculate difference between database-rows on output in an easy way?

[eluser]Richard Schumann[/eluser]
to bad for me - i did not figure out where to put ? before the for each in view ? or in the controller ?
basicly its logic what u type ...

right now in my controller i have it like this :

Code:

$this->db->from('weight');
$this->db->        where('user_id', $user_id);
$this->db->        order_by("timestamp", "desc");
$data['query'] = $this->db->get();

so as u can see i have just this $data['query'] what i print in view with a foreach end :-(