创建数据库和表

INSTALLED_APPS = [
    ‘django.contrib.admin‘,
    ‘django.contrib.auth‘,
    ‘django.contrib.contenttypes‘,
    ‘django.contrib.sessions‘,
    ‘django.contrib.messages‘,
    ‘django.contrib.staticfiles‘,

    # 加入下面这行
    ‘common.apps.CommonConfig‘,
]

from django.apps import AppConfig


class CommonConfig(AppConfig):
    name = ‘common‘

from django.db import models

# Create your models here.

from django.db import models
import datetime

class Customer(models.Model):
    name = models.CharField(max_length=200)

    phonenumber = models.CharField(max_length=200)

    address = models.CharField(max_length=200)

class Medicine(models.Model):
    # 药品名
    name = models.CharField(max_length=200)
    # 药品编号
    sn = models.CharField(max_length=200)
    # 描述
    desc = models.CharField(max_length=200)


class Order(models.Model):
    # 订单名
    name = models.CharField(max_length=200,null=True,blank=True)

    # 创建日期
    create_date = models.DateTimeField(default=datetime.datetime.now)

    # 客户
    customer = models.ForeignKey(Customer,on_delete=models.PROTECT)

    # 订单购买的药品，和Medicine表是多对多 的关系
    medicines = models.ManyToManyField(Medicine, through=‘OrderMedicine‘)

    # 为了提高效率，这里存放 订单 medicines 冗余数据
    medicinelist = models.CharField(max_length=2000, null=True, blank=True)


class OrderMedicine(models.Model):
    order = models.ForeignKey(Order, on_delete=models.PROTECT)
    medicine = models.ForeignKey(Medicine, on_delete=models.PROTECT)

    # 订单中药品的数量
    amount = models.PositiveIntegerField()

# 国家表
class Country(models.Model):
    name = models.CharField(max_length=100)

# country 字段是国家表的外键，形成一对多的关系
class Student(models.Model):
    name    = models.CharField(max_length=100)
    grade   = models.PositiveSmallIntegerField()
    country = models.ForeignKey(Country,
                on_delete = models.PROTECT,
                # 指定反向访问的名字
                related_name=‘students‘)

python manage.py makemigrations common

python manage.py migrate