SqlAlchemy初探

SqlAlchemy是Python下的一个成熟的ORM框架。下面我们对他的使用做一个简略的介绍。

0.安装

如果有pip，使用pip安装，更便捷。pip install sqlalchemy

也可以下载包安装。python setup.py install

 

1.连接配置

1 >>> from sqlalchemy import create_engine

2 >>> engine = create_engine('sqlite:///:memory:', echo=True)

3 MySql的连库字符串：mysql+pymysql://<username>:<password>@<host>/<dbname>[?<options>] 

2.模型配置

 1 >>> from sqlalchemy.ext.declarative import declarative_base

 2 >>> Base = declarative_base()

 3 >>> from sqlalchemy import Column, Integer, String

 4 >>> class User(Base):

 5 ...     __tablename__ = 'users'

 6 ...

 7 ...     id = Column(Integer, primary_key=True)

 8 ...     name = Column(String)

 9 ...     fullname = Column(String)

10 ...     password = Column(String)

11 ...

12 ...     def __repr__(self):

13 ...        return "<User(name='%s', fullname='%s', password='%s')>" % (

14 ...                             self.name, self.fullname, self.password)

15 

17 创建一个模型的实例：

18 >>> ed_user = User(name='ed', fullname='Ed Jones', password='edspassword')

19 >>> ed_user.name

20 'ed'

21 >>> ed_user.password

22 'edspassword'

23 >>> str(ed_user.id)

24 'None' 

3.数据查询

1 >>> from sqlalchemy.orm import sessionmaker

2 #两种建立session的方法：

3 >>> Session = sessionmaker(bind=engine)

4 #或者

5 >>> Session = sessionmaker()

6 >>> Session.configure(bind=engine)  # once engine is available

　　3.1 普通查询

 1 >>>session.query(user_alias, user_alias.name).all()/one()/first()

 2 >>>session.query(user_alias, user_alias.name).filter(User.fullname=='Ed Jones').filter(User.age [>,<,==,>=,<==]25).all()

 3 >>>query.filter(User.name == 'ed')

 4 >>>query.filter(User.name != 'ed')

 5 >>>query.filter(User.name.like('%ed%'))

 6 >>>query.filter(User.name.in_(['ed', 'wendy', 'jack']))

 7 >>>query.filter(~User.name.in_(['ed', 'wendy', 'jack']))

 8 >>>query.filter(User.name == None)

 9 >>>query.filter(User.name.is_(None))

10 >>>query.filter(User.name != None)

11 >>>query.filter(User.name.isnot(None))

12 >>>from sqlalchemy import and_

13 >>>query.filter(and_(User.name == 'ed', User.fullname == 'Ed Jones'))

14 >>>query.filter(User.name == 'ed', User.fullname == 'Ed Jones')

15 >>>query.filter(User.name == 'ed').filter(User.fullname == 'Ed Jones')

16 >>>from sqlalchemy import or_

17 >>>query.filter(or_(User.name == 'ed', User.name == 'wendy'))

18 >>>query.filter(User.name.match('wendy'))

 　　3.2关联查询

　　　　用到时候再补上。

4.更改提交