[Solved] Need help for AR query

[eluser]Unknown[/eluser]
Hi folks. I'm new in this forum and I currently learning CI.

I need some help for my Model AR query:

$this->load->library('encrypt');
$q = $this
->db
->where('email', $email)
->where('password', $this->encrypt->decode($password, $this->db->where('datecreation', 'email = '.$email.'')))
->limit('1')
->get('users');

As you can see, I use encrypt library to decode a password. I need to retrieve the 'datecreation' column as key for this decoding. So here is my question: How to extract the corresponding user 'datecreation' column into this query?

Thanks lot by advance

Best regards,
Patrick.