Where something and something SQL

[eluser]kolxoznik1[/eluser]
I have read user_guide and do not found WHERE something AND something.

So I need to check WHERE a = 3 and a = 5

so as I understand

$this->db->where('user_id', $user_id);
$this->db->where('follow_id', $follow_id);

two WHERE mean AND ?

Code:

function add_follow($user_id, $follow_id)
    {
        $this->db->select('user_id');
        $this->db->where('user_id', $user_id);
        $this->db->where('follow_id', $follow_id);
        $query = $this->db->get('user_follow');
        if ($query->num_rows() == 0) {
            $this->db->set('user_id', $user_id);
            $this->db->set('follow_id', $follow_id);
            $this->db->insert('user_follow');        
        }
        return FALSE;
    }

is it correct?