1.setting.py 配置

DATABASES = {
    'default': {
        'ENGINE': 'django.db.backends.', # 用什么数据库管理系统
        'NAME': '',                      # 数据库名称，假设用sqlite。要写完整路径
        'USER': '',                      # 假设用sqlite，这个不用写
        'PASSWORD': '',          # 假设用sqlite，这个不用写
        'HOST': '',                      # 告诉Django连接那一台. Not used with sqlite3. 假设用sqlite也空白
        'PORT': '',                      # 设置port。空白就是默认，一般用默认的即可了。对于sqlite没用。
    }
}

'ENGINE' 能够有：

'ENGINE' 数据库管理系统适配器适配器下载地址

django.db.backends.postgresql_psycopg2 PostgreSQL psycopg http://www.djangoproject.com/r/python-pgsql/.

django.db.backends.mysql MySQL MySQLdb http://www.djangoproject.com/r/python-mysql/

django.db.backends.sqlite3 SQLite

django.db.backends.oracle Oracle cx_Oracle http://www.djangoproject.com/r/python-oracle/

注意：用那个DBMS，就要安装相应DBMS的适配器。SQLite的，python默认已经装好了。

可用以下来命令測试数据库配置，假设没有显示错误信息。配置就是正确的。

>>> from django.db import connection

>>> cursor = connection.cursor()

2.创建APP

project跟APP的差别：一个是配置。一个是代码。
一个project能够包括非常多app以及它们的配置。一个app是一套Django功能的集合。通常包括模型和视图。按python的包结构的方式存在。

前面你能够创建app。可是假设要用模型，你就必须创建一个app。模型必须放在apps中。

创建一个“books”模型

python manage.py startapp books

它会创建一个books包，内容例如以下

books/

├── admin.py

├── __init__.py

├── models.py

├── tests.py

└── views.py

然后在settings.py中INSTALLED_APPS中加入 'books'。

3.定义模型，模型安装

样例：

在models.py 中加入

from django.db import models

class Publisher(models.Model):
    name = models.CharField(max_length=30)
    address = models.CharField(max_length=50)
    city = models.CharField(max_length=60)
    state_province = models.CharField(max_length=30)
    country = models.CharField(max_length=50)
    website = models.URLField()

class Author(models.Model):
    first_name = models.CharField(max_length=30)
    last_name = models.CharField(max_length=40)
    email = models.EmailField()

class Book(models.Model):
    title = models.CharField(max_length=100)
    authors = models.ManyToManyField(Author)
    publisher = models.ForeignKey(Publisher)
    publication_date = models.DateField()

Publisher模块相当于：

CREATE TABLE "books_publisher" (
    "id" serial NOT NULL PRIMARY KEY,
    "name" varchar(30) NOT NULL,
    "address" varchar(50) NOT NULL,
    "city" varchar(60) NOT NULL,
    "state_province" varchar(30) NOT NULL,
    "country" varchar(50) NOT NULL,
    "website" varchar(200) NOT NULL
);

注意：这里没有显示的为这些模型定义不论什么主键。除非指明，Django会自己主动为每一个模型生成一个自增长的单独主键 id

能够用以下的命令验证模型的有效性

python manage.py validate

能够用以下命令生成SQL语句。它这仅仅是生成SQL语句。不会运行

python manage.py sqlall books

假设想运行。运行以下语句（这个语句，在里加入新的模型或者app时才实用，改动删除模型syncdb不会做出不论什么反应）

python manage.py syncdb

4.数据库操作

（1）数据库插入，显示

>>> from books.models import *

>>> p1 = Publisher(name='Apress', address='2855 Telegraph Avenue',

... city='Berkeley', state_province='CA', country='U.S.A.',

... website='http://www.apress.com/')

>>> p1.save()

>>> p2 = Publisher(name="O'Reilly", address='10 Fawcett St.',

... city='Cambridge', state_province='MA', country='U.S.A.',

... website='http://www.oreilly.com/')

>>> p2.save()

>>> publisher_list = Publisher.objects.all()

>>> publisher_list

[<Publisher: Publisher object>, <Publisher: Publisher object>]

单单的p1=Publisher(...) 不会插入。必需要p1.save() 后才会真正生效

假设想一次性完毕插入运行以下的命令

>>> from books.models import *

>>> p1 = Publisher.objects.create(name='Apress',

... address='2855 Telegraph Avenue',

... city='Berkeley', state_province='CA', country='U.S.A.',

... website='http://www.apress.com/')

>>> p2 = Publisher.objects.create(name="O'Reilly",

... address='10 Fawcett St.', city='Cambridge',

... state_province='MA', country='U.S.A.',

... website='http://www.oreilly.com/')

>>> publisher_list = Publisher.objects.all()

>>> publisher_list

[<Publisher: Publisher object>, <Publisher: Publisher object>]

Publisher.objects.all()相当于 select

在输入publisher_list时，返回的对象名字都一样。不好分辨，解决方法就是，在模板类中加入__unicode__() 方法

如：

class Publisher(models.Model):
    name = models.CharField(max_length=30)
    address = models.CharField(max_length=50)
    city = models.CharField(max_length=60)
    state_province = models.CharField(max_length=30)
    country = models.CharField(max_length=50)
    website = models.URLField()

    def __unicode__(self):
        return self.name

这样又一次启动，输入以下命令，就能够分辨出来。

>>> from books.models import Publisher

>>> publisher_list = Publisher.objects.all()

>>> publisher_list

[<Publisher: Apress>, <Publisher: O'Reilly>]

（2）数据库更新

样例：

>>> p = Publisher(name='Apress',

... address='2855 Telegraph Ave.',

... city='Berkeley',

... state_province='CA',

... country='U.S.A.',

... website='http://www.apress.com/')

>>> p.save()

>>> p

<Publisher: Apress>

>>> p.id

3

>>> p.name = 'Apress Publishing'

>>> p.save()

>>> p

<Publisher: Apress Publishing>

注意：以下这样是更行不了的

>>> Publisher.objects.all()[0].name='AAAAAA'

>>> Publisher.objects.all()[0].save()

>>> Publisher.objects.all()[0]

<Publisher: Apress Publishing>

得要这样更新

>>> p = Publisher.objects.get(name='Apress')

>>> p

<Publisher: Apress>

>>> p.name = 'Apress Publishing'

>>> p.save()

>>> p

<Publisher: Apress Publishing>

上面的更行方法，用l了save()。这样无论有没有改过的数据。都会更行。能够用update(...)，它仅仅会更新要改的

>>> Publisher.objects.filter(id=1).update(name='Apress')

1

>>> Publisher.objects.all()

[<Publisher: Apress>, <Publisher: O'Reilly>]

可是update(),对结果集（QuerySet）有效，get()，[0]。无效

如以下的命令会报错

>>> Publisher.objects.get(id=1).update(name='Apress')

Traceback (most recent call last):

File "<console>", line 1, in <module>

AttributeError: 'Publisher' object has no attribute 'update'

（3）选择对象

Publisher.objects.all()显示全部对象

>>> Publisher.objects.all()

[<Publisher: Apress>, <Publisher: O'Reilly>]

Publisher.objects.filter(name='Apress')

Publisher.objects.filter(...) 筛选

>>> Publisher.objects.filter(name='Apress')

[<Publisher: Apress>]

filter(...) 能够有多个參数。相当与SQL中的AND

>>> Publisher.objects.filter(country="U.S.A.",state_province="CA")

[<Publisher: Apress>]

假设想使用SQL中的 LIKE 查询，要用 XX__contains

>>> Publisher.objects.filter(name__contains="press")

[<Publisher: Apress>]

name__contains="press" 相当与 LIKE “%press%”

（4）获取单个对象

filter 仅仅要满足条件的都会输出

获取单个对象用get

>>> Publisher.objects.get(name='Apress')

<Publisher: Apress>

假设满足的不止一个会有异常，假设没有会抛出DoesNotExist异常

>>> Publisher.objects.get(country='U.S.A.')

Traceback (most recent call last):

File "<console>", line 1, in <module>

File "/usr/lib64/python2.7/site-packages/django/db/models/manager.py", line 151, in get

return self.get_queryset().get(*args, **kwargs)

File "/usr/lib64/python2.7/site-packages/django/db/models/query.py", line 310, in get

(self.model._meta.object_name, num))

MultipleObjectsReturned: get() returned more than one Publisher -- it returned 2!

（5）数据库排序

用order_by

>>> Publisher.objects.order_by("name")

[<Publisher: Apress>, <Publisher: O'Reilly>]

倒叙，仅仅须要，加上“-”

>>> Publisher.objects.order_by("-name")

[<Publisher: O'Reilly>, <Publisher: Apress>]

（6）连锁查询

样例：

>>> Publisher.objects.filter(country="U.S.A.").order_by("-name")

[<Publisher: O'Reilly>, <Publisher: Apress>]

（7）限制返回查询

样例：

>>> Publisher.objects.order_by("-name")[0]

<Publisher: O'Reilly>

>>> Publisher.objects.order_by("-name")[0:2]

[<Publisher: O'Reilly>, <Publisher: Apress>]

（8）删除对象

用 delete()

>>> Publisher.objects.all()

[<Publisher: Apress>, <Publisher: O'Reilly>]

>>> Publisher.objects.filter(name='Apress').delete()

>>> Publisher.objects.all()

[<Publisher: O'Reilly>]

删除全部对象

>>> Publisher.objects.all().delete()

>>> Publisher.objects.all()

[]