In production or having important data in development you should take time to investigate the issue. In this case you most likely had created an empty migration, ran rake db:migrate, then added instructions to the migration, so you don't see a new field and further rake db:migrate does nothing. To resolve this issue you need to comment your change instructions, perform rake db:rollback, uncomment instructions and then rake db:migrate to apply instructions you missed.

Try to rebuild your database structure(WARNING: all db-data will be lost):

rake db:drop:all
rake db:create:all
rake db:migrate

If you use Rails < 4.1, don't forget to prepare test database:

rake db:test:prepare

This is the easiest solution since you are working with tutorial.