如何更改javascript消息框codeigniter的条件

I want to show message box with javascript with some codition from database, this is the example: controller

$email_cek     = $this->model_select->select_member('where email = "$email"');
    if($email_cek == 0){
    $facebook           = $this->input->post('facebook');
    $facebook_cek       = $this->model_select->select_member('where facebook = "$facebook"');
    if($facebook_cek == 0){
        //other script
    }else{
        echo "
        alert('You can't use that facebook account because the account has been used by another member! save aborted!');
        window.location.href='membership';
        ";
    }
    }else{
    echo "
    alert('Your e-mail is exist by another member! save aborted!');
    window.location.href='membership';
    ";
}

model

public function select_member($id=""){
    $data_member = $this->db->query("select * from member ".$id);
    return $data_member->result_array();
    }

I have two forms twitter and facebook, and the existing data in database. if input type same or exist in database, I want to display a message according to the data that already exists. but why the message always email messagebox show??

try model :

public function select_member($id=""){
    $data = $this->db->query("select * from member ".$id);
    return $data;
}

Controller :

$email_cek     = $this->model_select->select_member('where email = "$email"');
if($email_cek->num_rows() == 0){
    $facebook           = $this->input->post('facebook');
    $facebook_cek       = $this->model_select->select_member('where facebook = "$facebook"');
    if($facebook_cek->num_rows() == 0){
        //other script
    }else{
        echo "
        alert('You can't use that facebook account because the account has been used by another member! save aborted!');
        window.location.href='membership';
        ";
    }
}else{
    echo "
    alert('Your e-mail is exist by another member! save aborted!');
    window.location.href='membership';
    ";
}