title: How to auto-generate passwords in Rails Devise?
body: <p>I am trying out how Devise works with one of my projects for user authentication. There is a user requirement that their admin should be able to generate a batch of username and user's password from time to time, and then the admin will email the new username and password to his users.</p>
  
  <p>Assume the admin has the knowledge of direct SQL on the MySQL database, how can the generated usernames/passwords recognized by Devise? Thanks!</p>