Select Join for two columns in codeigniter

Hello everybody;

Code:

Table 1
   id product_name location added_by updated_by added date
   1  LENOVO       St 23    2        1          2016-08-26

Table 2
id first_name last_name email
1  John       Doe       [email protected]
2  Peter      Smith     [email protected]

I would like to know how to select data with codeigniter query in order to get result like this

Code:

product_name location added_by    updated_by
LENOVO       St 23    Peter Smith John Doe

I have tried with join but added_by column and updated_by column display same data.

I have got answer

$this->db->select('t1.product_name,t1.location, CONCAT(t2_1.first_name, " ", t2_1.last_name) AS added_by, CONCAT(t2_2.first_name, " ", t2_2.last_name) AS updated_by');
$this->db->from('Table 1 t1');
$this->db->join('Table 2 t2_1', 't2_1.id = t1.added_by', 'left');
$this->db->join('Table 2 t2_2', 't2_2.id = t1.updated_by', 'left');
$query = $this->db->get();
return $query->result();