CodeIgniter嵌套在where条件中

I want to run this query on CodeIgniter

select * from connections where (first_user=$u_id and second_user=$id) OR (first_user=$id and second_user=$u_id)

Controller I written for creating above code as follows

$where = array('first_user' => $this->session->userdata('u_id') , 'second_user'=> $this->uri->segment(4));
$or_where = array('first_user' => $this->uri->segment(4) , 'second_user'=> $this->session->userdata('u_id'));
$data['friendship']=$this->user_model->get_sql_select_data_or_where('connections', $where, $or_where, NULL, '1');

and the function get_sql_select_data_or_where is as follows

public function get_sql_select_data_or_where($tablename, $where = '', $or_where = '', $feild = '', $limit = '', $order_by = '', $like = '') {

    if (!empty($feild))
        $this->db->select($feild);

    if (empty($feild))
        $this->db->select();

    if (!empty($where))
        $this->db->where($where);

    if (!empty($or_where))
        $this->db->or_where($or_where);

    if (!empty($limit))
        $this->db->limit($limit);

    if (!empty($like))
        $this->db->like($like);

    if (!empty($order_by))
        $this->db->order_by($order_by);

    $this->db->from($tablename);
    $query = $this->db->get();
    return $query->result();
}

But when I print the query ,the result is as below

SELECT * FROM (`connections`) WHERE `first_user` = '28' AND `second_user` = '20' OR `first_user` = '20' OR `second_user` = '28' LIMIT 1 

Where I expected AND condition instead of second OR. What could possibly go wrong?

You can use this

 $where = "(first_user='".$this->session->userdata('u_id')."' AND second_user='". $this->uri->segment(4)."') OR ( second_user= '".$this->session->userdata('u_id')."' AND first_user= '".$this->uri->segment(4)."') ";

Referance : How to give two or where condition in mysql query in codeigniter

You can directly use:

$where = (first_user=$this->session->userdata('u_id') AND second_user= $this->uri->segment(4)) OR (first_user=$this->uri->segment(4) AND second_user=$this->session->userdata('u_id'));

Can refer to this link for reference Codeigniter select query with AND and OR condition