Пример учебника sqlalchemy не работает

Я пытаюсь разобраться в примере, приведенном в учебнике sqlalchemy , но получаю ошибки. Насколько я могу судить, я следую примеру до буквы. Вот код, который у меня есть на данный момент. Это не удается, когда я .first () после запроса БД.

Я использую версию 0.7.5 и python 2.7

from sqlalchemy                 import Column, Integer, String
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy                 import create_engine
from sqlalchemy.orm             import sessionmaker

engine = create_engine('sqlite:///:memory:', echo=True)
engine.execute("select 1").scalar() # works fine

Session = sessionmaker(bind=engine)
session = Session()
Base = declarative_base()

class User(Base):
    __tablename__ = 'users'

    id = Column(Integer, primary_key=True)
    name = Column(String)
    fullname = Column(String)
    password = Column(String)

    def __init__(self, name, fullname, password):
        self.name = name
        self.fullname = fullname
        self.password = password

    def __repr__(self):
       return "" % (self.name, self.fullname, self.password)

jeff_user = User("jeff", "Jeff", "foo")
session.add(jeff_user)

our_user = session.query(User).filter_by(name='jeff').first() # fails here

jeff_user.password = "foobar"

session.add_all([
                User('wendy', 'Wendy Williams', 'foobar'),
                User('mary', 'Mary Contrary', 'xxg527'),
                User('fred', 'Fred Flinstone', 'blah')])

session.dirty # shows nothing as dirty
session.new   # shows nothing as new

Вот сообщение об ошибке

2012-02-25 17:48:33,879 INFO sqlalchemy.engine.base.Engine BEGIN (implicit)
2012-02-25 17:48:33,886 INFO sqlalchemy.engine.base.Engine INSERT INTO users (name, fullname, password) VALUES (?, ?, ?)
2012-02-25 17:48:33,886 INFO sqlalchemy.engine.base.Engine ('jeff', 'Jeff', 'foo')
2012-02-25 17:48:33,887 INFO sqlalchemy.engine.base.Engine ROLLBACK
Traceback (most recent call last):
  File "learning_sql.py", line 35, in 
    our_user = session.query(User).filter_by(name='ed').first() # fails here
  File "/usr/local/lib/python2.7/dist-packages/sqlalchemy/orm/query.py", line 2024, in first
    ret = list(self[0:1])
  File "/usr/local/lib/python2.7/dist-packages/sqlalchemy/orm/query.py", line 1918, in __getitem__
    return list(res)
  File "/usr/local/lib/python2.7/dist-packages/sqlalchemy/orm/query.py", line 2092, in __iter__
    self.session._autoflush()
  File "/usr/local/lib/python2.7/dist-packages/sqlalchemy/orm/session.py", line 983, in _autoflush
    self.flush()
  File "/usr/local/lib/python2.7/dist-packages/sqlalchemy/orm/session.py", line 1559, in flush
    self._flush(objects)
  File "/usr/local/lib/python2.7/dist-packages/sqlalchemy/orm/session.py", line 1630, in _flush
    flush_context.execute()
  File "/usr/local/lib/python2.7/dist-packages/sqlalchemy/orm/unitofwork.py", line 331, in execute
    rec.execute(self)
  File "/usr/local/lib/python2.7/dist-packages/sqlalchemy/orm/unitofwork.py", line 475, in execute
    uow
  File "/usr/local/lib/python2.7/dist-packages/sqlalchemy/orm/mapper.py", line 2291, in _save_obj
    execute(statement, params)
  File "/usr/local/lib/python2.7/dist-packages/sqlalchemy/engine/base.py", line 1405, in execute
    params)
  File "/usr/local/lib/python2.7/dist-packages/sqlalchemy/engine/base.py", line 1538, in _execute_clauseelement
    compiled_sql, distilled_params
  File "/usr/local/lib/python2.7/dist-packages/sqlalchemy/engine/base.py", line 1646, in _execute_context
    context)
  File "/usr/local/lib/python2.7/dist-packages/sqlalchemy/engine/base.py", line 1639, in _execute_context
    context)
  File "/usr/local/lib/python2.7/dist-packages/sqlalchemy/engine/default.py", line 330, in do_execute
    cursor.execute(statement, parameters)
sqlalchemy.exc.OperationalError: (OperationalError) no such table: users u'INSERT INTO users (name, fullname, password) VALUES (?, ?, ?)' ('jeff', 'Jeff', 'foo')

Ожидаемый вывод такой

>>> our_user = session.query(User).filter_by(name='ed').first() 
BEGIN (implicit)
INSERT INTO users (name, fullname, password) VALUES (?, ?, ?)
('ed', 'Ed Jones', 'edspassword')
SELECT users.id AS users_id, users.name AS users_name, users.fullname AS users_fullname, users.password AS users_password
FROM users
WHERE users.name = ?
 LIMIT 1 OFFSET 0
('ed',)
>>> our_user

По какой-то причине мой код вызывает ОТКАТ, когда он должен быть ВЫБРАТЬ.