manage.py dbshell
  manage.py inspectdb
DATABASES = {
    'default': {
        'ENGINE': 'django.db.backends.postgresql',
        'NAME': 'db_dev',
        'USER': 'root',
        'PASSWORD': '',
        'HOST': '127.0.0.1',
        'PORT': '5432',
    }
}
from django.apps import AppConfig
class TestappConfig(AppConfig):
    #nameにprojectを追加する
    name = 'testprj.testapp'
INSTALLED_APPS = [
    'testprj.testapp.apps.TestappConfig',
]
from django.contrib import admin
from django.urls import path
urlpatterns = [
    path('admin/', admin.site.urls),
]
#djangoにUserというモデル名は避けるべき
from django.db import models
class AppUser(models.Model):
    id = models.BigAutoField(primary_key=True)
    created_at = models.DateTimeField()
    updated_at = models.DateTimeField()
    name = models.CharField(max_length=256)
class Meta:
    managed = False
    db_table = 'users'
def __str__(self):
  return self.name
from django.contrib.auth.models import *
from django.contrib import admin
from .models.app_user import AppUser
class UserAdmin(admin.ModelAdmin):
    list_display = ('id', 'name', 'created_at', 'updated_at', )
    list_display_links = ('name', )
admin.site.register(AppUser, UserAdmin)
manage.py createsuperuser