How to use multiple databases from different sites in Drupal?

Question

Drupal

Good afternoon, please tell me, is it possible somehow, with the help of a module, or something else, to connect one site to the database of another, namely, for example, let's say creating a view, indicate somewhere in it that information is taken from such and such a database .
That. all available fields were displayed from the selected base, either from both bases, or from multiple bases.
In other words, combine for output, editing, searching, etc. several databases from different absolutely Drupal 7 sites

Answer 1

Isn't it easier to make the necessary representations on donor sites, and show this data on the receiving site via AJAX?

Answer 2

https://www.drupal.org/node/18429