get DB handler in CodeIgniter for stand-alone Libraries

We were working on a project where some developers were working with CI and were developing libraries there, and some developers were developing stand-alone libraries. But both groups were working on the same project.
At some point we needed all those stand-alone libraries to be used in CI as well.
For common code it’s not a big deal, the only problem which took a little bit of time to figure out was using the DataBase. We didin’t want to make new DB connections, so how could we use the current connection, inside an stand-alone code.
The answer is pretty easy, CI’s DB class has a non-documented attribute which returns back the DB handler.
or if you have multiple DB cnnections that would be :
$this->dbw->conn_id;
and then you can easily pass the DB connection to regular mysql_query function like this :
and as an example :