joining.py

# vim: set fileencoding=utf-8 :
from __future__ import absolute_import, division

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


engine = create_engine('sqlite://')

Base = declarative_base()

class Model(Base):

    __tablename__ = 'model'

    id = Column(Integer, primary_key=True)


Base.metadata.create_all(bind=engine)
connection = engine.connect()
Session = sessionmaker(bind=engine)
session = Session()
trans = connection.begin()

assert session.query(Model).count() == 0
model = Model()
session.add(model)

session.commit()

trans.rollback()
session.close()
connection.close()

session = Session()
assert session.query(Model).count() == 0