【Flask】Sqlalchemy 增删该查操作

### sqlalchemy 增删改查操作， 通过session来进行操作。

 # coding:utf-8
 # Author: liangjun.

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

 HOSTNAME = '127.0.0.1'
 PORT = 3306
 DATABASE = 'sqlalchemy_first'
 USERNAME = 'root'
 PASSWORD = ''

 DB_URI = 'mysql+pymysql://{username}:{password}@{host}:{port}/{dbname}?charset=utf8'.format(
         username=USERNAME, password=PASSWORD, host=HOSTNAME, port=PORT, dbname=DATABASE
 )
 engine = create_engine(DB_URI)
 Base = declarative_base(engine)
 Session = sessionmaker(engine)
 session = Session()

 # 创建ORM模型
 class Person(Base):
     __tablename__ = 'person'
     id = Column(Integer, primary_key=True, autoincrement=True)
     name = Column(String(length=50))
     age = Column(Integer)

     def __repr__(self):
         return "Person<name:{}, age{}>".format(self.name, self.age)

 def add_data():
     p1 = Person(name='saber', age=18)
     p2 = Person(name='slamdunk', age=18)
     # 添加一条
     session.add(p1)
     # 添加多条记录
     session.add(p1, p2)
     session.commit()

 def update_data():
     person = session.query(Person).first()
     person.name = 'saber007'
     session.commit()

 def search_data():
     # 查找所有
     persons_1 = session.query(Person).all()
     for person in persons_1:
         print person

     # filter_by
     persons_2 = session.query(Person).filter_by(name='saber').all()
     for _p in persons_2:
         print _p

     # filter
     persons_3 = session.query(Person).filter(Person.name == 'saber').all()
     for _p in persons_3:
         print _p

     # get
     # 根据主键查找, 如没有则返回None
     person = session.query(Person).get(1)
     print "---------------get------------------"
     print person

     # first
     # 获取结果集中的第一条
     person = session.query(Person).first()
     print person

 def delete_data():
     person = session.query(Person).first()
     session.delete(person)
     session.commit()

 if __name__ == "__main__":
     # add_data()
     # search_data()
     # update_data()
     delete_data()