Codeigniter: Select from multiple tables

The example in the User Guide should explain this:

$this->db->select('*'); // <-- There is never any reason to write this line!
$this->db->from('blogs');
$this->db->join('comments', 'comments.id = blogs.id');

$query = $this->db->get();

// Produces:
// SELECT * FROM blogs
// JOIN comments ON comments.id = blogs.id

See the whole thing under Active Record page in the User Guide.

I think the question was not so much about joins as how to display values from two different tables - the User Guide doesn't seem to explain this.

Here's my take:

    $this->db->select('u.*, c.company, r.description');
    $this->db->from('users u, company c, roles r');
    $this->db->where('c.id = u.id_company');
    $this->db->where('r.permissions = u.permissions');
    $query = $this->db->get();

Just add the other table to the "->from()" method. Something like:

 $this->db->select('t1.field, t2.field2')
          ->from('table1 AS t1, table2 AS t2')
          ->where('t1.id = t2.table1_id')
          ->where('t1.user_id', $user_id);

I think the syntax is incorrect. You need to select one record. I have two tables, and I have an id from one table transfer by parameter, and the relation of both tables.