Hogyan tudom az alábbi kódot jól megírni?

$result = $this->db->select('u.*, sum(a.advance) as advance, sum(p.price) as price')

->from('advance a, products p, users u')

->where('a.user_id = u.id')

->where('p.user_id = u.id')

->group_by('u.name','desc')

->get();

if($result->num_rows() > 0){

return $result->result();

} else {

return false;

}