from sqlalchemy import create_engine, Column, Integer
from sqlalchemy.types import Interval
from sqlalchemy.orm import sessionmaker
from sqlalchemy.ext.declarative import declarative_base
from datetime import timedelta, datetime

engine = create_engine('sqlite:///:memory:')
Base = declarative_base()
Session = sessionmaker(bind=engine)
session = Session()

class IntervalItem(Base):
    __tablename__ = 'interval'
    id = Column(Integer, primary_key=True)
    interval = Column(Interval)

Base.metadata.create_all(engine)

epoch = datetime.utcfromtimestamp(0)
delta = timedelta(1)
one_day = datetime.utcfromtimestamp(86400)
print "Date to be stored in database:", epoch + delta
print "Timedelta from date:", one_day - epoch


interval = IntervalItem(interval=delta)
session.add(interval)
session.flush()
session.expunge(interval)
i = session.query(IntervalItem).first()
print "Timedelta from database:", i.interval