Get last executed query in MySQL with PHP CodeIgniter

Question

In my_model.php, I have:

$query1 = ( ...something... );
$query2 = ( ...something... );
$variables = ( .... something .... );
$this->db->query(" $query1 ... $variables .. $query2", array( $variables, ... ));

I need the last query executed right after the code snippet above. How can I get the last query I ran in MySQL in Windows and Linux?