how to access database created with dbforge

Hello!

I'm kinda new with dbforge. I have some questions.

1. If a database is created using dbforge, can you use query builder for the dynamic database(insert, update, delete)?  

2. If you can't use query builder on the dbforge created database, do you just have to build queries with "$this->db->query("YOUR QUERY")"?

3. How do you "select" the dbforge created database to preform queries on? ("$this->db->query('use db2');" so, this is the 'use' statement and it works the same as in SQL syntax?)

Thank you!