[SOLVED] to view a list using models

[eluser]Unknown[/eluser]
Hello;
I got a program for library. and i had some models. one of them is "book". and it has "is_available" (boolean) field.
and i want to take a "available books list".
can you help me about this please?
if i want to view a specific book i do it like this:
$this->db->where("book_id", $this->input->post("book_id"));
$query = $this->db->get('book');