Can you use JOIN in a recursive function PHP/MySQL?

[erix]

I have the following table.\[code\]CREATE TABLE IF NOT EXISTS `omc_schedule` ( `id` int(11) NOT NULL AUTO_INCREMENT, `name` varchar(255) NOT NULL, `trainer_id` int(11) NOT NULL, `course` varchar(255) NOT NULL, `capacity` int(11) NOT NULL, `active` tinyint(1) NOT NULL DEFAULT '1', `parentid` int(10) NOT NULL, `order` int(11) NOT NULL, `booked` int(5) NOT NULL, `type` varchar(255) NOT NULL, PRIMARY KEY (`id`)) ...\[/code\]I can use the following function to generate an array tree.\[code\] function generateTree(&$tree, $parentid = 0) { $this->db->select('*'); $this->db->where ('parentid',$parentid);$this->db->where ('active','1'); $this->db->order_by('order asc, parentid asc'); $res = $this->db->get('omc_schedule'); if ($res->num_rows() > 0) { foreach ($res->result_array() as $r) { // push found result onto existing tree $tree[$r['id']] = $r; // create placeholder for children $tree[$r['id']]['children'] = array(); // find any children of currently found child $this->generateTree($tree[$r['id']]['children'],$r['id']); } } $res->free_result(); return $tree; }\[/code\]Now I want to join to a trainer table to get trainer's name.\[code\]CREATE TABLE IF NOT EXISTS `omc_trainer` ( `id` int(10) unsigned NOT NULL AUTO_INCREMENT, `trainer_name` varchar(50) NOT NULL, `trainer_image` varchar(100) NOT NULL, `video_url` text NOT NULL, `desc` text NOT NULL, PRIMARY KEY (`id`))\[/code\]Now I tried to join in different ways, but I am not able to get trainer's name in every array.Is there any way I can use JOIN to get trainer's name in a recursive function?Above function is CodeIgniter, but please ignore it. Thanks in advance.