django怎么直接使用数据库（Django教程03通过实体创建数据库表）

Django教程——01安装使用Django教程——02连接初始化数据库，今天小编就来说说关于django怎么直接使用数据库?下面更多详细答案一起来看看吧!

django怎么直接使用数据库

Django教程——01安装使用

Django教程——02连接初始化数据库

接着上文连接好数据库后，下面讲下如何通过Django将工程里实体对象生成数据库表

一、定义实体

在polls应用下创建数据库实体

其中Django数据库字段属性设置教程 https://docs.djangoproject.com/en/4.0/ref/models/fields/ Model field reference | Django documentation | Django

polls/models.py

from django.db import models # Create your models here. class Question(models.Model): question_text=models.CharField(max_length=200) pub_date=models.DateTimeField('date published') def __str__(self): return self.question_text 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

二、使用实体对象

1、在项目settings.py里引入应用

mysite/settings.py

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

2、初始化模型对象

python manage.py makemigrations polls

执行该命令后，就会在polls/migrations/0001_initial.py文件下生成实体对象代码，用于生成数据库表用

3、生成建表sql

python manage.py sqlmigrate polls 0001

执行结果如下

BEGIN; -- -- 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 ); -- -- Create model Choice -- CREATE TABLE "polls_choice" ( "id" serial NOT NULL PRIMARY KEY, "choice_text" varchar(200) NOT NULL, "votes" integer NOT NULL, "question_id" integer NOT NULL ); ALTER TABLE "polls_choice" ADD CONSTRAINT "polls_choice_question_id_c5b4b260_fk_polls_question_id" FOREIGN KEY ("question_id") REFERENCES "polls_question" ("id") DEFERRABLE INITIALLY DEFERRED; CREATE INDEX "polls_choice_question_id_c5b4b260" ON "polls_choice" ("question_id"); COMMIT;

4、同步建表语句到数据库

python manage.py migrate

执行完后，数据库就会增加上面两张表

三、shell操作

执行shell命令

python manage.py shell

就可以通过控制台进行编写调用模型的api

>>> from polls.models import Choice, Question # Import the model classes we just wrote. # No questions are in the system yet. >>> Question.objects.all() <QuerySet []> # Create a new Question. # Support for time zones is enabled in the default settings file, so # Django expects a datetime with tzinfo for pub_date. Use timezone.now() # instead of datetime.datetime.now() and it will do the right thing. >>> from django.utils import timezone >>> q = Question(question_text="What's new?", pub_date=timezone.now()) # Save the object into the database. You have to call save() explicitly. >>> q.save() # Now it has an ID. >>> q.id

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