MYSQL / Query Builder Class help

How do I do a SELECT query that queries columns in 2 tables?  eg SELECT t1.column1, table2.column2 from t1, t2  using Query Builder

If you know how to do this in plain MySQL, you'll know that you need a JOIN statement.

Example in query builder, with tables "posts" and "comments":

PHP Code:

$this->db
->select ('t1.title, t2.comment_date')
->from('posts t1')
->join('comments t2','t2.post_id = t1.id')
->order_by('t2.comment_date','DESC');
$query = $this->db->get();
if ($query->num_rows() == 0) {
   return FALSE;
}
else {
   return $query->result();
} 


To apply old style SQL, just do this:

PHP Code:

$sql = "SELECT * FROM posts ORDER BY id";
$records = $this->db->query($sql)->result();
//$records is an array of objects