DATABASES = {'default': {'ENGINE': 'django.db.backends.sqlite3','NAME': os.path.join(BASE_DIR, 'db.sqlite3'),}
}

DATABASES = {'default': {'ENGINE': 'django.db.backends.postgresql','NAME': 'mydatabase','USER': 'mydatabaseuser','PASSWORD': 'mypassword','HOST': '127.0.0.1','PORT': '5432',}
}

ENGINE: 'django.db.backends.sqlite3'，'django.db.backends.postgresql'， 'django.db.backends.mysql'，'django.db.backends.oracle'
NAME:数据库的名称如果使用SQLite，数据库将是您计算机上的一个文件, 此时NAME 应该是该文件的完全绝对路径，包括文件名。默认值，将文件存储在项目目录中。os.path.join(BASE_DIR, 'db.sqlite3')

django.contrib.admin - 管理网站
django.contrib.auth - 认证系统
django.contrib.contenttypes - 内容类型的框架
django.contrib.sessions - 会话框架
django.contrib.messages - 消息框架
django.contrib.staticfiles - 一个用于管理静态文件的框架

python manage.py migrate

from django.db import modelsclass Question(models.Model):question_text = models.CharField(max_length=200)pub_date = models.DateTimeField('date published')class Choice(models.Model):question = models.ForeignKey(Question, on_delete=models.CASCADE)choice_text = models.CharField(max_length=200)votes = models.IntegerField(default=0)

INSTALLED_APPS = ['polls.apps.PollsConfig','django.contrib.admin','django.contrib.auth','django.contrib.contenttypes','django.contrib.sessions','django.contrib.messages','django.contrib.staticfiles',
]

python manage.py makemigrations polls

Migrations for 'polls':polls/migrations/0001_initial.py:- Create model Choice- Create model Question- Add field question to choice

python manage.py sqlmigrate polls 0001

BEGIN;
--
-- Create model Choice
--
CREATE TABLE "polls_choice" ("id" serial NOT NULL PRIMARY KEY,"choice_text" varchar(200) NOT NULL,"votes" integer NOT NULL
);
--
-- Create model Question
--
CREATE TABLE "polls_question" ("id" serial NOT NULL PRIMARY KEY,"question_text" varchar(200) NOT NULL,"pub_date" timestamp with time zone NOT NULL
);
--
-- Add field question to choice
--
ALTER TABLE "polls_choice" ADD COLUMN "question_id" integer NOT NULL;
ALTER TABLE "polls_choice" ALTER COLUMN "question_id" DROP DEFAULT;
CREATE INDEX "polls_choice_7aa0f6ee" ON "polls_choice" ("question_id");
ALTER TABLE "polls_choice"ADD CONSTRAINT "polls_choice_question_id_246c99a640fbbd72_fk_polls_question_id"FOREIGN KEY ("question_id")REFERENCES "polls_question" ("id")DEFERRABLE INITIALLY DEFERRED;COMMIT;

 python manage.py check

python manage.py migrate

python manage.py shell

# 导入
>>> from polls.models import Question, Choice# questions的内容信息
>>> Question.objects.all()
<QuerySet []># 创建一条记录并保存
# 使用timezone.now()代替datetime.datetime.now()
>>> from django.utils import timezone
>>> q = Question(question_text="What's new?", pub_date=timezone.now())
>>> q.save()# 查看属性值
>>> q.id
1
>>> q.question_text
"What's new?"
>>> q.pub_date
datetime.datetime(2017, 6, 25, 4, 1, 46, 582600, tzinfo=<UTC>)# 修改属性值并保存
>>> q.question_text = "what is your name?"
>>> q.save()# questions的内容信息
>>> Question.objects.all()
<QuerySet [<Question: Question object>]>

import datetimefrom django.db import models
from django.utils.encoding import python_2_unicode_compatible
from django.utils import timezone# 如果要使得__str__能够在python2生效就使用该装饰器
@python_2_unicode_compatible
class Question(models.Model):question_text = models.CharField(max_length=200)pub_date = models.DateTimeField('date published')def __str__(self):return self.question_textdef was_published_recently(self):return self.pub_date >= timezone.now() - datetime.timedelta(days=1)@python_2_unicode_compatible
class Choice(models.Model):question = models.ForeignKey(Question, on_delete=models.CASCADE)choice_text = models.CharField(max_length=200)votes = models.IntegerField(default=0)def __str__(self):return self.choice_text

# 导入
>>> from polls.models import Question, Choice# 查询question, 此时可以看到显示和之前不一样了
>>> Question.objects.all()
<QuerySet [<Question: what is your name?>]># 使用filter()可以过滤查找id为1的数据
>>> Question.objects.filter(id=1)
<QuerySet [<Question: what is your name?>]>
# 使用__startwith
>>> Question.objects.filter(question_text__startswith = 'what')
<QuerySet [<Question: what is your name?>]># 判断该question是否是今年发布
# 使用__year
>>> from django.utils import timezone
>>> current_year = timezone.now().year
>>> Question.objects.get(pub_date__year=current_year)
<Question: what is your name?# 用pk(primary key的缩写)查询主键为1的question
# 相当于 Question.objects.get(id=1)
>>> Question.objects.get(pk=1)
<Question: what is your name?># 测试一下刚才的函数
>>> q = Question.objects.get(pk=1)
>>> q.was_published_recently()
True# 使用  引用该表作为外键的表名_set  来获取对应的外键信息(反向操作)
>>> q = Question.objects.get(pk=1)
>>> q.choice_set.all()
<QuerySet []># 反向操作创建
>>> q.choice_set.create(choice_text='Not much', votes=0)
<Choice: Not much>
>>> q.choice_set.create(choice_text='The sky', votes=0)
<Choice: The sky>
>>> c = q.choice_set.create(choice_text='Just hacking again', votes=0)
>>> c
<Choice: Just hacking again># 得到的choice可以正向查看question
>>> c.question
<Question: what is your name?># _set的操作
>>> q.choice_set.all()
<QuerySet [<Choice: Not much>, <Choice: The sky>, <Choice: Just hacking again>]>
>>> q.choice_set.count()
3
>>> q.choice_set.filter(choice_text__startswith='Just')
<QuerySet [<Choice: Just hacking again>]># 正向操作relationship
# 使用双下划线来分割关系, 可以递进多层都没有关系, 只要你想
>>> Choice.objects.filter(question__pub_date__year=current_year)
<QuerySet [<Choice: Not much>, <Choice: The sky>, <Choice: Just hacking again>]># 删除一波数据
>>> c = q.choice_set.get(pk=3)
>>> c
<Choice: Just hacking again>
>>> c.delete()
(1, {'TestModel.Choice': 1})
>>> q.choice_set.count()
2

python manage.py createsuperuser

python manage.py runserver

http://127.0.0.1:8000/admin

from django.contrib import admin
from .models import Questionadmin.site.register(Question)