python ORM

python下的orm基本操作(1)--Mysql下的CRUD简单操作(含源码DEMO)

　　系统centos

       refer:http://docs.sqlalchemy.org/en/latest/orm/tutorial.html

       

 

一，准备环境

 

       1.安装mysql-server (在此之前请准备好Python的环境)

       2.安装mysql-python

centos：yum install sqlalchemy -y 

       3.安装sqlalchemy 

准备环境OK之后，安装sqlalchemy

这个yum安装总是失败，就去官网下载的文件，解压安装了。

 

参考的解决方案：http://stackoverflow.com/questions/1972259/cannot-open-include-file-config-win-h-no-such-file-or-directory-while-inst

环境都准备OK之后，我们来大致看一下如何使用sqlalchemy 的ORM

 

二，实际操作

1 创建engine对象

　　这里，engine类似我们的连接字符串，它指示了你会连接到哪种类型的数据库，用户名，密码，地址等，这里，我示例的是mysql数据库，

# -*- coding: UTF-8 -*-

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

engine = create_engine('mysql://root:[email protected]:3306/test?charset=utf8',echo=True)

关于其它类型的数据库的连接字符串的写法，参考：

http://docs.sqlalchemy.org/en/rel_1_0/core/engines.html#sqlalchemy.create_engine

 

2.定义映射关系

#declare a Mapping,this is the class describe map to table column
Base = declarative_base()

 

3.定义连接管理器

#connect session to active the action
Session = sessionmaker(bind=engine)
session = Session()

 

4.表结构与类结构映射

class Person(Base):
    __tablename__ = 'Person'
    Id = Column(Integer, primary_key=True,autoincrement=True)
    Pname = Column(String,nullable=False,default='')
    Address = Column(String,nullable=False,default='')
    Age = Column(Integer,nullable=False,default=0)

    def __repr__(self):
        return 'the info is ID %s Pname is %s Address is %s and Age is %s' % \
        (self.Id, self.Pname, self.Address,  self.Age)

 

根据以上的代码，就可以完整的操作Mysql了，完整的代码如下：

# -*- coding: UTF-8 -*-

__author__ = 'Bruce'
from sqlalchemy import create_engine
from sqlalchemy import Column, Integer, String
from sqlalchemy.orm import sessionmaker
from sqlalchemy.ext.declarative import declarative_base

#declare the connecting to the server
engine = create_engine('mysql://account:[email protected]:3306/test?charset=utf8',echo=False)

#declare a Mapping,this is the class describe map to table column
Base = declarative_base()

#connect session to active the action
Session = sessionmaker(bind=engine)
session = Session()

class Person(Base):
    __tablename__ = 'Person'
    Id = Column(Integer, primary_key=True,autoincrement=True)
    Pname = Column(String,nullable=False,default='')
    Address = Column(String,nullable=False,default='')
    Age = Column(Integer,nullable=False,default=0)

    def __repr__(self):
        return 'the info is ID %s Pname is %s Address is %s and Age is %s' % \
        (self.Id, self.Pname, self.Address,  self.Age)

if __name__ == '__main__':
    #add one
    p = Person(Pname='bruce', Address='beijing', Age=22)
    session.add(p)
    session.commit()

    #query one
    p_1 = session.query(Person).filter_by(Pname='bruce').first()
    print p_1

    #delete one
    p_2 = session.query(Person).filter_by(Pname='bruce').first()
    if p_2:
        session.delete(p_2)
        session.commit()

    #edit one
    p_3 = session.query(Person).filter_by(Pname='bruce').first()
    if p_3:
        p_3.Age = 55
        session.commit()