作了最基本的操作，找找感觉。。

#coding=utf-8from datetime import datetimefrom sqlalchemy import (MetaData, Table, Column, Integer, Numeric, String, Boolean,                         DateTime, ForeignKey, create_engine, CheckConstraint)from sqlalchemy import (insert, select, update, delete, text, desc, cast, and_, or_, not_)from sqlalchemy import (Table, ForeignKeyConstraint)from sqlalchemy.sql import funcfrom sqlalchemy.exc import IntegrityErrorfrom sqlalchemy.ext.declarative import declarative_basefrom sqlalchemy.orm import (relationship, backref, sessionmaker)Base = declarative_base()class Cookie(Base):    __tablename__ = 'cookies'    cookie_id = Column(Integer(), primary_key=True)    cookie_name = Column(String(50), index=True)    cookie_recipe_url = Column(String(255))    cookie_sku = Column(String(55))    quantity = Column(Integer())    unit_cost = Column(Numeric(12, 2))    def __repr__(self):        return "Cookie(cookie_name='{self.cookie_name}', " \               "cookie_recipe_url='{self.cookie_recipe_url}', " \               "cookie_sku='{self.cookie_sku}', " \               "quantity={self.quantity}, " \               "unit_cost={self.unit_cost})".format(self=self)class User(Base):    __tablename__ = 'users'    user_id = Column(Integer(), primary_key=True)    username = Column(String(15), nullable=False, unique=True)    email_address = Column(String(255), nullable=False)    phone = Column(String(20), nullable=False)    password = Column(String(25), nullable=False)    created_on = Column(DateTime(), default=datetime.now)    updated_on = Column(DateTime(), default=datetime.now, onupdate=datetime.now)    def __repr__(self):        return "User(username='{self.username}', " \               "email_address='{self.email_address}', " \               "phone='{self.phone}', " \               "password='{self.password}')".format(self=self)class Order(Base):    __tablename__ = 'orders'    order_id = Column(Integer(), primary_key=True)    user_id = Column(Integer(), ForeignKey('users.user_id'))    shipped = Column(Boolean(), default=False)    user = relationship("User", backref=backref('orders', order_by=order_id))    def __repr__(self):        return "Order(user_id={self.user_id}, " \               "shipped={self.shipped})".format(self=self)class LineItem(Base):    __tablename__ = 'line_items'    line_item_id = Column(Integer(), primary_key=True)    order_id = Column(Integer(), ForeignKey('orders.order_id'))    cookie_id = Column(Integer(), ForeignKey('cookies.cookie_id'))    quantity = Column(Integer())    extended_cost = Column(Numeric(12, 2))    order = relationship("Order", backref=backref('line_items', order_by=line_item_id))    cookie = relationship("Cookie", uselist=False)    def __repr__(self):        return "LineItems(order_id={self.order_id}, " \               "cookie_id={self.cookie_id}, " \               "quantity={self.quantity}, " \               "extended_cost={self.extended_cost})".format(self=self)engine = create_engine('mysql+pymysql://connection_str/cookies')Base.metadata.create_all(engine)Session = sessionmaker(bind=engine)session = Session()'''cc_cookie = Cookie(cookie_name='chocolate chip',                   cookie_recipe_url='http://www.baidu.com/',                   cookie_sku='CC01',                   quantity=12,                   unit_cost=0.50)session.add(cc_cookie)session.commit()print(cc_cookie.cookie_id)dcc = Cookie(cookie_name='dark chocolate chip',             cookie_recipe_url='http://some.aweso.me/cookie/recipe_dark.html',             cookie_sku='CC02',             quantity=1,             unit_cost=0.75)mol = Cookie(cookie_name='molasses',             cookie_recipe_url='http://some.aweso.me/cookie/recipe_molasses.html',             cookie_sku='MOL01',             quantity=1,             unit_cost=0.80)session.add(dcc)session.add(mol)session.flush()print(dcc.cookie_id)print(mol.cookie_id)c1 = Cookie(cookie_name='peanut butter',            cookie_recipe_url='http://some.aweso.me/cookie/peanut.html',            cookie_sku='PB01',            quantity=24,            unit_cost=0.25)c2 = Cookie(cookie_name='oatmeal raisin',            cookie_recipe_url='http://some.okay.me/cookie/raisin.html',            cookie_sku='EWW01',            quantity=100,            unit_cost=1.00)session.bulk_save_objects([c1, c2])session.commit()print(c1.cookie_id)'''cookies = session.query(Cookie).all()print(cookies)for cookie in session.query(Cookie):    print(cookie)