This will be less about a question and more of a way to document things. I had been attempting to use drush (Drush 11 and 12) after installing a new copy of Drupal. It kept throwing Error: Undefined Constant PDO::MYSQL_ATTR_USE_BUFFERED_QUERY Yet the site worked fine. I checked php.net and Drupal Answers but to no avail. What did I need to do to get Drush working correctly?