暂未找到一个app应用多个数据库的方法，可使用app与数据库映射的方式去做

• settings.py文件配置数据库

  DATABASES = {
      # 默认数据库配置
      'default': {
          'ENGINE': 'django.db.backends.mysql',
          'NAME': 'database_name', # 自定义数据库名称
          'USER': 'db_username',
          'PASSWORD': 'db_user_password',
          'HOST': '127.0.0.1',
          'PORT': '3306',
          'CONN_MAX_AGE': 30,
          'OPTION': {
              'init_command': 'SET default_storage_engine=INNODB'
          }
      },
      'business': { #secondDb代表第二个数据库的配置#该名称可自定义
          'ENGINE': 'django.db.backends.mysql',
          'NAME': 'second_db_name',
          'USER': 'db_username ',
          'PASSWORD': 'db_user_password',
          'HOST': '127.0.0.1',
          'PORT': '3306',
          'CONN_MAX_AGE': 30,
          'OPTION': {
              'init_command': 'SET default_storage_engine=INNODB'
          },
      },
  #...略
  }
  ....
  # 数据库路由指向
  DATABASE_ROUTERS = ['config.database_router.DatabaseRouter']
  # 数据库与app映射
  DATABASE_APPS_MAPPING = {
      # example:
      # 'app_name':'database_name',
      'business': 'business',
  }
  # 配置不允许迁移的app下的model
  APPS_NOT_ALLOW_MIGRATE = ['business'] 
  

• 在settings.py所在目录新建文件database_router.py

  from django.conf import settings
  
  DATABASE_MAPPING = settings.DATABASE_APPS_MAPPING
  
  
  class DatabaseRouter(object):
      """
      A router to control all database operations on models for different
      databases.
      In case an app is not set in settings.DATABASE_APPS_MAPPING, the router
      will fallback to the `default` database.
      Settings example:
      DATABASE_APPS_MAPPING = {'app1': 'db1', 'app2': 'db2'}
      """
      using = "django4"
  
      def db_for_read(self, model, **hints):
          """"Point all read operations to the specific database."""
          if model._meta.app_label in DATABASE_MAPPING:
              return DATABASE_MAPPING[model._meta.app_label]
          return None
  
      def db_for_write(self, model, **hints):
          """Point all write operations to the specific database."""
          if model._meta.app_label in DATABASE_MAPPING:
              return DATABASE_MAPPING[model._meta.app_label]
          return None
  
      def allow_relation(self, obj1, obj2, **hints):
          """Allow any relation between apps that use the same database."""
          db_obj1 = DATABASE_MAPPING.get(obj1._meta.app_label)
          db_obj2 = DATABASE_MAPPING.get(obj2._meta.app_label)
          if db_obj1 and db_obj2:
              if db_obj1 == db_obj2:
                  return True
              else:
                  return False
          return None
  
      def allow_syncdb(self, db, model):
          """Make sure that apps only appear in the related database."""
          if db in DATABASE_MAPPING.values():
              return DATABASE_MAPPING.get(model._meta.app_label) == db
          elif model._meta.app_label in DATABASE_MAPPING:
              return False
          return None
  
      def allow_migrate(self, db, app_label, model=None, **hints):
          """
          Make sure the auth app only appears in the 'auth_db'
          database.
          """
          if db in DATABASE_MAPPING.values():
              return DATABASE_MAPPING.get(app_label) == db
          elif app_label in DATABASE_MAPPING:
              return False
          return None
  

• 在相应的models.py表中指定app_label

  class Business(models.Model):
      # 地址
      id = UUIDField(primary_key=True, verbose_name='id')
      type = CharField(default='d2d', max_length=200, verbose_name='类型')
      ....
      class Meta:
          # 指定绑定的app
          app_label = 'business'
          db_table = 'vll'
          verbose_name = '业务'
          verbose_name_plural = '业务'