Etwas

from sqlalchemy import *from sqlalchemy.orm import *engine = create_engine('sqlite:///')metadata = MetaData(engine)# Tablesuser_table = Table('user', metadata,        Column('id', Integer, primary_key=True),        Column('login', String(8), nullable=False, unique=True))item_table = Table('item', metadata,        Column('id', Integer, primary_key=True),        Column('address', String(50), nullable=False, unique=True))tag_table = Table('tag', metadata,        Column('id', Integer, primary_key=True),        Column('tag', String(50), nullable=False, unique=True))user_tag_item_table = Table('user_tag_item', metadata,        Column('id', Integer, primary_key=True),        Column('user_id', Integer, ForeignKey('user.id')),        Column('item_id', Integer, ForeignKey('item.id')),        Column('tag_id', Integer, ForeignKey('tag.id')))metadata.create_all()Session = sessionmaker(bind=engine, autoflush=True, transactional=True)# Objectsclass User(object):    def __init__(self, login):        self.login = login    def __repr__(self):        return "User(%r)" % self.loginclass Item(object):    def __init__(self, address):        self.address = address    def __repr__(self):        return "Item(%r)" % self.addressclass Tag(object):    def __init__(self, tag):        self.tag = tag    def __repr__(self):        return "Tag(%r)" % self.tagclass UserTagItem(object):    def __init__(self, user, tag, item):        self.user = user.id        self.tag = tag.id        self.item = item.id    def __repr__(self):        return "UserTagItem(%r %r %r)" % (self.user, self.tag, self.item)# Mappers ???