for fun, you can also manipulate these in the console by making a model class for them…
class SchemaMigration < ActiveRecord::Base; self.primary_key = :version; end
then you can do SchemaMigration.all, SchemaMigration.last.delete, etc.
Really just a substitute for using SQL, and it is very rare that you would need to mess around at this low level… generally a bad idea but cool to see how to do it 🙂