Flask 如何组织数据库模型

要在db中创建新表，我编写如下内容：

class Cat(db.Model):
    id = db.Column(db.Integer, primary_key=True)
    name = db.Column(db.String(40))
    age = db.Column(db.String(40))
    born_date = db.Column(db.DateTime, default=datetime.datetime.utcnow)
    is_feline = db.Column(db.Boolean)

class Dog(db.Model):
    id = db.Column(db.Integer, primary_key=True)
    name = db.Column(db.String(40))
    age = db.Column(db.String(40))
    born_date = db.Column(db.DateTime, default=datetime.datetime.utcnow)
    wave_tail = db.Column(db.Boolean)

只创建了两个表。猫和狗。经典的一个，来自教程

我想做这样的事

class Animal(object):
    id = db.Column(db.Integer, primary_key=True)
    name = db.Column(db.String(40))
    age = db.Column(db.String(40))
    born_date = db.Column(db.DateTime, default=datetime.datetime.utcnow)

    common_functions

class Cat extends Animal:
      is_feline = db.Column(db.Boolean)

      def override common_functions
      def specific functions

class Dog extends Animal:
      wave_tail = db.Column(db.Boolean)

只创建了两个表。猫和狗

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或者有没有一个地方可以让我学到这些。SQLAlchemy文档非常庞大…

同时从SQLAlchemy模型类和父类继承实体：

class Animal(object):
    id = db.Column(db.Integer, primary_key=True)
    name = db.Column(db.String(40))
    age = db.Column(db.String(40))
    born_date = db.Column(db.DateTime, default=datetime.datetime.utcnow)

    def hi(self):
        print 'hello!'


class Cat(Animal, db.Model):
    __tablename__ = 'cats'
    is_feline = db.Column(db.Boolean)

    def hi(self):
        print 'cat'

    def hello(self):
        print 'hello'


class Dog(Animal, db.Model):
    __tablename__ = 'dogs'
    wave_tail = db.Column(db.Boolean)