Is it best practice to have more than one table in a Codeigniter model?

I have a question about Jamie Rumbelow's MY_Model and models generally.

MY_Model provides a protected variable that holds the name of the table. I want to use it but I want my model to handle 3 tables.

Can a model handle more than one table?

Is it good practice to do this or is it better to have a model per database table?

By default, MY_Model doesn't support multiple tables, however, you can very easily create methods - I like to call them scopes - to link to other tables in an efficient and elegant manner.

Let's say we have a post_model.php that needs to pull in data from the categories table. I'll assume that we want to bring in our category.name based on the post.category_id.

class Post_model extends MY_Model
{
    public function with_category()
    {
        $this->db->join('categories', 'categories.id = post.category_id', 'left');
        $this->db->select('categories.name AS category_name');

        return $this;
    }
}

We can then use our with_category() method (chained alongside all our built-in MY_Model methods) to pull out our category info:

$this->post_model->with_category()
                 ->get_all();

Or with get_by():

$this->post_model->with_category()
                 ->get_by('status', 'open');

Scoping is a cool way of introducing other tables into your models, while still getting to use all the cool stuff MY_Model provides.