Drush not selecting database
What you are seeing above is a bug in Drush where Drush cannot bootstrap the database of a Drupal site if the database credentials are correct, but the database itself is empty.  To fix this problem:


If your database is empty, run "drush site-install" to create a database.
If your database is not empty, check the settings of your database prefix, and make sure that it is correct.


This was recently fixed in https://github.com/drush-ops/drush/pull/1442.