orm的操作：

settings：

"""Django settings for about_exam project.Generated by ‘django-admin startproject‘ using Django 1.11.26.For more information on this file, seehttps://docs.djangoproject.com/en/1.11/topics/settings/For the full list of settings and their values, seehttps://docs.djangoproject.com/en/1.11/ref/settings/"""import os# Build paths inside the project like this: os.path.join(BASE_DIR, ...)#定义项目根目录：BASE_DIR = os.path.dirname(os.path.dirname(os.path.abspath(__file__)))# Quick-start development settings - unsuitable for production# See https://docs.djangoproject.com/en/1.11/howto/deployment/checklist/# SECURITY WARNING: keep the secret key used in production secret!SECRET_KEY = ‘07k_$&dsr2qjyw=*oz#bum20gtj^6k_c!#u2%7ixbad7q51zpr‘# SECURITY WARNING: don‘t run with debug turned on in production!DEBUG = TrueALLOWED_HOSTS = []# Application definition#定义注册的app：INSTALLED_APPS = [    ‘django.contrib.admin‘,    ‘django.contrib.auth‘,    ‘django.contrib.contenttypes‘,    ‘django.contrib.sessions‘,    ‘django.contrib.messages‘,    ‘django.contrib.staticfiles‘,    ‘app01.apps.App01Config‘,]MIDDLEWARE = [    ‘django.middleware.security.SecurityMiddleware‘,    ‘django.contrib.sessions.middleware.SessionMiddleware‘,    ‘django.middleware.common.CommonMiddleware‘,    ‘django.middleware.csrf.CsrfViewMiddleware‘,    ‘django.contrib.auth.middleware.AuthenticationMiddleware‘,    ‘django.contrib.messages.middleware.MessageMiddleware‘,    ‘django.middleware.clickjacking.XFrameOptionsMiddleware‘,]ROOT_URLCONF = ‘about_exam.urls‘#定义中间件：TEMPLATES = [    {        ‘BACKEND‘: ‘django.template.backends.django.DjangoTemplates‘,        ‘DIRS‘: [os.path.join ( BASE_DIR, ‘templates‘ )]        ,        ‘APP_DIRS‘: True,        ‘OPTIONS‘: {            ‘context_processors‘: [                ‘django.template.context_processors.debug‘,                ‘django.template.context_processors.request‘,                ‘django.contrib.auth.context_processors.auth‘,                ‘django.contrib.messages.context_processors.messages‘,            ],        },    },]WSGI_APPLICATION = ‘about_exam.wsgi.application‘# Database# https://docs.djangoproject.com/en/1.11/ref/settings/#databases#定义使用默认的数据库：DATABASES = {    ‘default‘: {        ‘ENGINE‘: ‘django.db.backends.sqlite3‘,        ‘NAME‘: os.path.join(BASE_DIR, ‘db.sqlite3‘),    }}# Password validation# https://docs.djangoproject.com/en/1.11/ref/settings/#auth-password-validatorsAUTH_PASSWORD_VALIDATORS = [    {        ‘NAME‘: ‘django.contrib.auth.password_validation.UserAttributeSimilarityValidator‘,    },    {        ‘NAME‘: ‘django.contrib.auth.password_validation.MinimumLengthValidator‘,    },    {        ‘NAME‘: ‘django.contrib.auth.password_validation.CommonPasswordValidator‘,    },    {        ‘NAME‘: ‘django.contrib.auth.password_validation.NumericPasswordValidator‘,    },]# Internationalization# https://docs.djangoproject.com/en/1.11/topics/i18n/LANGUAGE_CODE = ‘en-us‘TIME_ZONE = ‘UTC‘USE_I18N = TrueUSE_L10N = TrueUSE_TZ = True# Static files (CSS, JavaScript, Images)# https://docs.djangoproject.com/en/1.11/howto/static-files/#定义静态文件：STATIC_URL = ‘/static/‘orm表数据：

 models：

from django.db import models# Create your models here.#定义班级表：class Classes(models.Model):    c_name = models.CharField(max_length=32)    #定义班级和老师是多对多关系ManyToManyField：    teachers = models.ManyToManyField("Teacher")#定义老师表：class Teacher(models.Model):    t_name = models.CharField(max_length=32)    #定义性别长度字段默认是1、有选择的1代表男和2代表女：    sex = models.CharField(max_length=1,choices=(("1","男"),("2","女")))    #定义年龄IntegerField整数：    age = models.IntegerField()#定义学生表：class Student(models.Model):    s_name = models.CharField(max_length=32)    score = models.IntegerField()    #定义学生表多对一班级表、on_delete=models.CASCADE级联删除：    my_class = models.ForeignKey("Classes",on_delete=models.CASCADE)