Topic: Populating a devise user table

I have installed devise which I hope to use for authentication.

In the user table, devise requires 'reset_password_token' to be unique, so how is this initialized?

If I install devise with an already populated user table, the migration fails because the field is blank when added by the migration, so  'reset_password_token' is not unique.

So I install devise with an empty user table, I now need to insert user records, can I insert anything 'unique' into the reset_password_token field, for example the user email?

If not, how do I insert user records into the users table from an already existing user table?

Thanks in advance for any help. -- Fred