Connecting to multiple databases ?

[eluser]spaquet[/eluser]
I read many posts on this forum but for now it does not seem to be working at all...

My application uses an ERP as backend and offer to some users a easy way to get data from it and track some of their activity on the side of this ERP, reason why there is a second database (to manange CI_Session, user activity and some requests that are not part of the ERP).

What I've done:

I added a second database in database.php (sugarcrm) and have the following code for my user controller :

Code:

Class User_model extends CI_Model {

    private $db_erp;

    function __construct() {
        // Call the Model constructor
        parent::__construct();

        $this->db_erp = $this->load->database('sugarcrm', TRUE);
    }

    public function validates_user_from_erp($matricule, $password) {
        $sql = "SELECT * FROM users JOIN users_cstm ON users.id=users_cstm.id_c ";
        $sql += "WHERE users_cstm.matricule_c=" + $matricule + " AND ";
        $sql += "users_cstm.password_c=md5('" + $password + "');";

        $query = $this->db_erp->query($sql);
        
        if ($query->num_rows == 1) {
            return true;
        }
        
        return false;
    }

I made sure the database user connect to the database and that the query is valid (I tested in on the database).

Now when calling alidates_user_from_erp from my login controller

Code:

public function validate_credentials() {
        $this->output->enable_profiler(TRUE);

        $this->form_validation->set_rules('username', 'Utilisateur', 'required');
        $this->form_validation->set_rules('password', 'Mot de passe', 'required');

        if ($this->form_validation->run() == FALSE) {
            $this->index();
        } else {
            $this->load->model('User_model');
            
            //Check if user is active and if his/her credentials are valid
            $username = $this->input->post('username'); // aka matricule
            $password = $this->input->post('password');
            
            if( $this->User_model->validates_user_from_erp($username, $password) ) {
                
                redirect('dashboard');
                    
            } else {
                $this->index();
            }
        }
    }

I have the following error message :

Trying to get property of non-object

refering to the line

$query->num_rows == 1

of my User model.

It looks like the $query object is not a database object as expected and thus I can not use database methods on it.

Any help is welcome as I have the feeling I've done what I read in CI User Guide and several posts from this forum.