在settings中配置多个数据库：

DATABASES = {
        'default': {
            'ENGINE': 'django.db.backends.mysql',
            'NAME': "主从数据库名称",
            'USER': '用户名',
            'PASSWORD': "你的密码",
            'HOST': "主数据库ip地址",
            'PORT': '3306',
            "OPTIONS":{"init_command":"SET default_storage_engine=INNODB;"}
        },
        'slave': {
            'ENGINE': 'django.db.backends.mysql',
            'NAME': "从数据库名称",
            'USER': '用户名',
            'PASSWORD': "你的密码",
            'HOST': "从数据库ip地址",
            'PORT': '3306',
            "OPTIONS":{"init_command":"SET default_storage_engine=INNODB;"}
        }

        }


DATABASE_ROUTERS = ['project_name.database_router.DatabaseAppsRouter']
DATABASE_APPS_MAPPING = {
    # example:
    #'app_name':'database_name',
    'app1': 'default',   #主数据库
    'app2': 'slave',   #从数据库
}

在settings的同级目录下新建database_router.py文件，并输入以下代码：

from django.conf import settings
DATABASE_MAPPING = settings.DATABASE_APPS_MAPPING


class DatabaseAppsRouter(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'}
    """

    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

注意：
1.配置完成后，终端里的迁移命令变更为：
app1迁移主数据库：
]# python manage.py makemigrations app1
]# python manage.py migrate

app1迁移主数据库：
]# python manage.py makemigrations app2
]# python manage.py migrate --database=slave

(如果不是defalut(默认数据库）要在命令后边加 --database=数据库对应的settings.py中的名称 如： --database=db1 或 --database=db2)

2.数据库orm操作变更：
查询
YourModel.objects.using('db1').all()
或者 YourModel.objects.using('db2').all()

保存 或 删除
user_obj.save(using='new_users')
user_obj.delete(using='legacy_users')

参考：https://code.ziqiangxuetang.com/django/django-multi-database.html