Python DB operation

mysql

http://www.cnblogs.com/zhangzhu/archive/2013/07/04/3172486.html

1、连接到本机上的MYSQL。
首先打开DOS窗口，然后进入目录mysql\bin，再键入命令mysql -u root -p，回车后提示你输密码.注意用户名前可以有空格也可以没有空格，但是密码前必须没有空格，否则让你重新输入密码。

例1：建立一个名为xhkdb的数据库
   mysql> create database xhkdb;

py-mysql

http://www.runoob.com/python/python-mysql.html

python操作mysql数据库

Python 标准数据库接口为 Python DB-API，Python DB-API为开发人员提供了数据库应用编程接口。

Python 数据库接口支持非常多的数据库，你可以选择适合你项目的数据库：

Python DB-API使用流程：

• 引入 API 模块。
• 获取与数据库的连接。
• 执行SQL语句和存储过程。
• 关闭数据库连接。

#!/usr/bin/python
# -*- coding: UTF-8 -*-

import MySQLdb

# 打开数据库连接
db = MySQLdb.connect("localhost", "testuser", "test123", "TESTDB", charset='utf8' )

# 使用cursor()方法获取操作游标
cursor = db.cursor()

# 使用execute方法执行SQL语句
cursor.execute("SELECT VERSION()")

# 使用 fetchone() 方法获取一条数据
data = cursor.fetchone()

print "Database version : %s " % data

# 关闭数据库连接
db.close()

flask sqlalchemy orm

http://www.sqlalchemy.org/

The Python SQL Toolkit and Object Relational Mapper

SQLAlchemy is the Python SQL toolkit and Object Relational Mapper that gives application developers the full power and flexibility of SQL.

It provides a full suite of well known enterprise-level persistence patterns, designed for efficient and high-performing database access, adapted into a simple and Pythonic domain language.

SQLALCHEMY'S PHILOSOPHY

SQL databases behave less like object collections the more size and performance start to matter; object collections behave less like tables and rows the more abstraction starts to matter. SQLAlchemy aims to accommodate both of these principles.

SQLAlchemy considers the database to be a relational algebra engine, not just a collection of tables. Rows can be selected from not only tables but also joins and other select statements; any of these units can be composed into a larger structure. SQLAlchemy's expression language builds on this concept from its core.

SQLAlchemy is most famous for its object-relational mapper (ORM), an optional component that provides the data mapper pattern, where classes can be mapped to the database in open ended, multiple ways - allowing the object model and database schema to develop in a cleanly decoupled way from the beginning.

SQLAlchemy's overall approach to these problems is entirely different from that of most other SQL / ORM tools, rooted in a so-called complimentarity- oriented approach; instead of hiding away SQL and object relational details behind a wall of automation, all processes are fully exposed within a series of composable, transparent tools. The library takes on the job of automating redundant tasks while the developer remains in control of how the database is organized and how SQL is constructed.

The main goal of SQLAlchemy is to change the way you think about databases and SQL!

Read some key features of SQLAlchemy, as well as what people are saying about SQLAlchemy.

例子

http://docs.jinkan.org/docs/flask-sqlalchemy/quickstart.html

from flask import Flask
from flask.ext.sqlalchemy import SQLAlchemy

app = Flask(__name__)
app.config['SQLALCHEMY_DATABASE_URI'] = 'sqlite:////tmp/test.db'
db = SQLAlchemy(app)

class User(db.Model):
    id = db.Column(db.Integer, primary_key=True)
    username = db.Column(db.String(80), unique=True)
    email = db.Column(db.String(120), unique=True)

    def __init__(self, username, email):
        self.username = username
        self.email = email

    def __repr__(self):
        return '<User %r>' % self.username

>>> from yourapplication import db
>>> db.create_all()

砰，你的数据库就好了。现在来创建一些用户:

>>> from yourapplication import User
>>> admin = User('admin', 'admin@example.com')
>>> guest = User('guest', 'guest@example.com')

但是它们还不在数据库中，所以让我们确保它们被添加进去:

>>> db.session.add(admin)
>>> db.session.add(guest)
>>> db.session.commit()

访问数据库中的内容易如反掌:

>>> users = User.query.all()
[<User u'admin'>, <User u'guest'>]
>>> admin = User.query.filter_by(username='admin').first()
<User u'admin'>

参考：

http://www.pythondoc.com/flask-sqlalchemy/config.html

https://stackoverflow.com/questions/33738467/how-do-i-know-if-i-can-disable-sqlalchemy-track-modifications