code analysis

Hello,

I am learning CI code tutorial that I do not understand.  Can anyone help me understand this CI code?

PHP Code:

$data = $this->fetch_data_from_db($update_id); 


Where this code comes from : fetch_data_from_db( ) ?

I search the user guide: http://www.codeigniter.com/user_guide/  and do not find the codes.

Another one:

PHP Code:

$data['query'] = $this->_custom_query($mysql_query); 


Where this code comes from : _custom_query(); ?

I search the user guide: http://www.codeigniter.com/user_guide/  and do not find the codes.

" If I looks more intelligence please increase my reputation."

Gee maybe methods in your own model!

What did you Try? What did you Get? What did you Expect?

Joined CodeIgniter Community 2009.  ( Skype: insitfx )