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

 >>> from sqlalchemy import create_engine
 >>> engine = create_engine('sqlite:///:memory:', echo=True)
 MySql的连库字符串：mysql+pymysql://<username>:<password>@<host>/<dbname>[?<options>] 

2.模型配置

 >>> from sqlalchemy.ext.declarative import declarative_base
 >>> Base = declarative_base()
 >>> from sqlalchemy import Column, Integer, String
 >>> class User(Base):
 ...     __tablename__ = 'users'
 ...
 ...     id = Column(Integer, primary_key=True)
 ...     name = Column(String)
 ...     fullname = Column(String)
 ...     password = Column(String)
 ...
 ...     def __repr__(self):
 ...        return "<User(name='%s', fullname='%s', password='%s')>" % (
 ...                             self.name, self.fullname, self.password)

 创建一个模型的实例：
 >>> ed_user = User(name='ed', fullname='Ed Jones', password='edspassword')
 >>> ed_user.name
 'ed'
 >>> ed_user.password
 'edspassword'
 >>> str(ed_user.id)
 'None' 

3.数据查询

 >>> from sqlalchemy.orm import sessionmaker
 #两种建立session的方法：
 >>> Session = sessionmaker(bind=engine)
 #或者
 >>> Session = sessionmaker()
 >>> Session.configure(bind=engine)  # once engine is available

　　3.1 普通查询

 >>>session.query(user_alias, user_alias.name).all()/one()/first()
 >>>session.query(user_alias, user_alias.name).filter(User.fullname=='Ed Jones').filter(User.age [>,<,==,>=,<==]25).all()
 >>>query.filter(User.name == 'ed')
 >>>query.filter(User.name != 'ed')
 >>>query.filter(User.name.like('%ed%'))
 >>>query.filter(User.name.in_(['ed', 'wendy', 'jack']))
 >>>query.filter(~User.name.in_(['ed', 'wendy', 'jack']))
 >>>query.filter(User.name == None)
 >>>query.filter(User.name.is_(None))
 >>>query.filter(User.name != None)
 >>>query.filter(User.name.isnot(None))
 >>>from sqlalchemy import and_
 >>>query.filter(and_(User.name == 'ed', User.fullname == 'Ed Jones'))
 >>>query.filter(User.name == 'ed', User.fullname == 'Ed Jones')
 >>>query.filter(User.name == 'ed').filter(User.fullname == 'Ed Jones')
 >>>from sqlalchemy import or_
 >>>query.filter(or_(User.name == 'ed', User.name == 'wendy'))
 >>>query.filter(User.name.match('wendy'))

　　3.2关联查询

　　　　用到时候再补上。

4.更改提交