change_column_default

# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 349
      def change_column_default(table_name, column_name, default_or_changes) #:nodoc:
        default = extract_new_default_value(default_or_changes)
        change_column table_name, column_name, nil, default: default
      end