join of users and users_groups as 1 row

Hello,
Using CodeIgniter 3.0.3 I make join of users and users_groups tables with command

PHP Code:

    $this->db->join($this->ion_auth_config_tables['users_groups'], $this->ion_auth_config_tables['users_groups'] . '.user_id = ' . $this->ion_auth_config_tables['users'] . '.id', 'left'); 


and I get sql like

Code:

SELECT bp_users.*
FROM `bp_users`
LEFT JOIN `bp_users_groups` ON `bp_users_groups`.`user_id` = `bp_users`.`id`

as any user can be member of several groups in result set for any such user I get several rows.
I would like for any user to get 1 row with subarray of his groups.
Sure, I can make such grouping manually. But can I to make such using CodeIgniter db/sql methods ?

  Thanks!