How do I access the database from a library class?

[eluser]hal10001[/eluser]
I created my own library class, which works fine, but I just can't get connected to the database to run a query. From a function I try to load in the "database" library, but get the following:

Unable to load the requested class: database

This is the basic code:

Code:

class MyClass {

    function myFunction()
    {
        $CI =& get_instance();
        $CI->load->library( 'database' );

        $query = $this->db->query( 'SOME QUERY GOES HERE' );
        return count( $query->result() );
    }
    
}

How do I do this from a library class, and do I need a model, or can I just run the query like normal when using the database class? Thanks!