#一张表对应一个类class UserInfo(Base):    #把表名赋给静态字段    __tablename__ = ‘userinfo‘    #序号nid，用户名username，密码password，邮箱email，创建时间ctime    #一行数据就是一个对象    nid = Column(Integer, primary_key=True, autoincrement=True)    username = Column(String(32))    password = Column(String(32))    email = Column(String(32))    ctime = Column(TIMESTAMP)    #建立组合索引，这里是方便在登陆采用不同的登陆方式也能更好的索引数据库    #用户名+密码   和   邮箱+密码   两种组合索引    __table_args__ = (        Index(‘ix_user_pwd‘, ‘username‘, ‘password‘),        Index(‘ix_email_pwd‘, ‘email‘, ‘password‘),    )

class NewsType(Base):    __tablename__ = ‘newstype‘    nid = Column(Integer, primary_key=True, autoincrement=True)    caption = Column(String(32))

class News(Base):    __tablename__ = ‘news‘    nid = Column(Integer, primary_key=True, autoincrement=True)    #建立外键---两个    user_info_id = Column(Integer, ForeignKey("userinfo.nid"))    news_type_id = Column(Integer, ForeignKey("newstype.nid"))    ctime = Column(TIMESTAMP)    title = Column(String(32))    url = Column(String(128))    content = Column(String(150))

class Favor(Base):    #点赞表    __tablename__ = ‘favor‘    nid = Column(Integer, primary_key=True, autoincrement=True)    #点赞者id    user_info_id = Column(Integer, ForeignKey("userinfo.nid"))    #信息id    news_id = Column(Integer, ForeignKey("news.nid"))    ctime = Column(TIMESTAMP)    #建立联合唯一索引    __table_args__ = (        UniqueConstraint(‘user_info_id‘, ‘news_id‘, name=‘uix_uid_nid‘),    ) 

class Comment(Base):    __tablename__ = ‘comment‘    nid = Column(Integer, primary_key=True, autoincrement=True)    #评论者id    user_info_id = Column(Integer, ForeignKey("userinfo.nid"))    #评论的信息id    news_id = Column(Integer, ForeignKey("news.nid"))    #如果为None，就是评论文章，如果是数字就是回复某个人    reply_id = Column(Integer, ForeignKey("comment.nid"), nullable=True, default=None)    #顶一下    up = Column(Integer)    #踩一下    down = Column(Integer)    #创建时间    ctime = Column(TIMESTAMP)    #发表设备：手机，电脑，苹果....    device = Column(String(32))    #发表内容    content = Column(String(150))