Can one app have multiple databases?

Can an app use two different databases?

There's nothing wrong with accessing two databases from one application. It's a model used frequently. It's not uncommon to have a Node server access both Mongodb and Redis, using each for their strengths. You just have to tie data relations together in your app instead of in the database.

Can a system have multiple databases?

By splitting the data into multiple databases, different applications only access the data that they need to be accessing. +1. The common terms for this technique are sharding and partitioning. Large scale applications don't keep all of their data in a single database.

Can a website have multiple databases?

You would just create two data sources and potentially two data access layers if you want to take it that far. At least for . Net/C#/VB.Net this wouldn't be a problem. I'm not sure I understand the benefit in this case but if you feel you have a good reason to separate the database, there's no reason it can't be done.

Can we connect 2 database in Web application?

Yes it is possible. But you need to be extra careful while writing the data tovthe database from the app. But to read the data, it will be easy. Just use the same credentials while connecting to the database using any backend programming languages.