Specify sub-ordinate database name to connect to through Bookshelf model

[Akhil-gif777]

Issue Description

I could not specify a sub-db under the main-db to make query calls as bookshelf does not provide an option to mention a sub-db in its model. I have a db structure like below :

-mainDB
- sub-db-1
- table-1
- table-2
- sub-db-2
- table-1
- table-2
- sub-db-3
- table-1
- table-2

Expected Behavior

I would like to mention a sub-db in bookshelf model after connecting to the main-db then make query calls to tables inside the sub-db.