我的Rails 4.2.6应用程序使用两个数据库。我只能用一个来测试吗?

I have a web application in Rails 4.2.6 that was originally using MongoDB (through Mongoid 5) as its main database. However, now I need to connect to a MySQL database to only read some additional data for my app.I have a web application in Rails 4.2.6 that wa