[web-devel] [Yesod] Teach me how to write to access second database.

Hi I write an application, which must to access 2 databases. 1st is main database for this application. 2nd database is used as main database by another application. Could you teach me how to write to access 2nd database? Since there is no access to the 2nd database only partially, I'm a little problem in an ad hoc way.