$data = array(
        'name' => $name ,
        'email' => $email,
        'time' => NOW()
        );
        $this->db->insert('mytable', $data);

$data = array(
        'name' => $name ,
        'email' => $email,
        );
        $this->db->set('time', 'NOW()', FALSE);
        $this->db->insert('mytable', $data);

$data = array(
            'name' => $name ,
            'email' => $email,
            'time' => NOW(), FALSE
            );

$data = array(
    'name' => $name,
    'email' => $email
);

$this->db->set('time', 'NOW()', FALSE);
$this->db->insert('mytable', $data);

$this->db->set('time', 'NOW()', FALSE);
$this->db->insert('mytable', $data);

$this->db->set('time', 'NOW() + INTERVAL 1 DAY', FALSE);
$this->db->insert('mytable', $data);

$data = array('created_on' => date('Y-m-d H:i:s'));

$data = array(
'created_on' => date('Y-m-d H:i:s',now())
);

$data = array(
            'name' => $name ,
            'email' => $email,
            'time' =>date('Y-m-d H:i:s')
            );
            $this->db->insert('mytable', $data);

$this->db->set('time', 'NOW()', FALSE);

$this->db->last_query();

public function set($key, $value = '', $escape = TRUE)
{
    $key = $this->_object_to_array($key);

    if ( ! is_array($key))
    {
        $key = array($key => $value);
    }

    foreach ($key as $k => $v)
    {
        if ($escape === FALSE)
        {
            $this->ar_set[$this->_protect_identifiers($k)] = $v;
        }
        else
        {
            $this->ar_set[$this->_protect_identifiers($k, FALSE, TRUE)] = $this->escape($v);
        }
    }

    return $this;
}

$this->db->set(array(
    'name' => $name ,
    'email' => $email,
    'time' => 'NOW()'), '', FALSE)->insert('mytable');

$this->db->set(array(
    'name' => $name ,
    'email' => $email))->set(array('time' => 'NOW()'), '', FALSE)->insert('mytable');

$this->load->helper('date');

$data = array(
  'created' => now(),
  'modified' => now()
);

$this->db->insert('TABLENAME', $data);

$data['created_on'] = $row->noinmyssql;
$this->db->insert($data);