Django3.2的ORM增删改查

14.2ORM

ORM可以帮助我们做两件事

• 创建，修改，删除数据库中的表(不用你写SQL语句)
• 操作表中的数据(不用写SQL语句)

14.2.1创建数据库

create database gx_day15 DEFAULT CHARSET utf8 COLLATE utf8_general_ci;

14.2.2django连接数据库

settings.py文件中

DATABASES = {
    'default': {
        'ENGINE': 'django.db.backends.mysql',
        'NAME':'gx_day15',
        'USER':'root',
        'PASSWORD':"123456",
        "HOST":"127.0.0.1",
        "PORT":"3306"
    }
}

14.2.3django操作表

• 创建表
• 删除表
• 修改表

1.创建表:在app01/models.py文件中

from operator import mod
from django.db import models

# Create your models here.
class UserInfo(models.Model):
    name=models.CharField(max_length=32)
    password=models.CharField(max_length=64)
    age=models.IntegerField()

执行命令:

python manage.py makemigrations
python manage.py migrate
注意:app需要提前注册

2.添加表

class Department(models.Model):
    title=models.CharField(max_length=16)

class Role(models.Model):
    caption=models.CharField(max_length=16)

再次执行命令:

python manage.py makemigrations
python manage.py migrate

3.删除表

class Department(models.Model):
    title=models.CharField(max_length=16)

#class Role(models.Model):
#    caption=models.CharField(max_length=16)

再次执行命令:

python manage.py makemigrations
python manage.py migrate

4.删除表的字段

from operator import mod
from django.db import models

# Create your models here.
class UserInfo(models.Model):
    name=models.CharField(max_length=32)
    password=models.CharField(max_length=64)
    #age=models.IntegerField()

再次执行命令:

python manage.py makemigrations
python manage.py migrate

5.增加表的字段

from operator import mod
from django.db import models

# Create your models here.
class UserInfo(models.Model):
    name=models.CharField(max_length=32)
    password=models.CharField(max_length=64)
    #age=models.IntegerField()
    # 1.没有默认值增加字段
    # 执行命令会出现选项1和选项2,选择选项1,输入默认值
    size=models.IntegerField()
    # 2.有默认值增加字段
    age=models.IntegerField(default=2)
    # 3.增加字段允许内容为空
    data=models.IntegerField(null=True,blank=True)

再次执行命令:

python manage.py makemigrations
python manage.py migrate

15.orm增删改查

urls.py

from django.contrib import admin
from django.urls import path
from app01 import views

urlpatterns = [
    path('orm/', views.orm),
]

views.py

#第一种引入方式，指定引入
from app01.models import Department,UserInfo
#第二种引入方式，引入全部
#from app01 import models
from django.shortcuts import render,HttpResponse,redirect
def orm(request):
    # Department.objects.create(title="销售部")
    # Department.objects.create(title="IT部")
    # Department.objects.create(title="运营部")
    #1.新建
    UserInfo.objects.create(name="test",password="123456",age=20)
    
    #2.删除
    UserInfo.objects.filter(id=1).delete()
    UserInfo.objects.all().delete()

    #3.获取数据
    #data_list=[对象,行,行] QuerySet类型
    data_list=UserInfo.objects.all()
    for obj in data_list:
        print(obj.id,obj.name,obj.password,obj.age)
    
    # 4.更新数据
    UserInfo.objects.filter(id=1).update(age=999)
   
    return HttpResponse("成功")

models.py

from operator import mod
from django.db import models

class UserInfo(models.Model):
    name=models.CharField(max_length=32)
    password=models.CharField(max_length=64)
    age=models.IntegerField(default=2)
   
class Department(models.Model):
    title=models.CharField(max_length=16)

访问127.0.0.1:8000/orm,返回成功