DATABASES = {
    'default': {
        'ENGINE': 'django.db.backends.sqlite3',         
        'NAME': 'db.sqlite3',
    }
}

DATABASES = {
    'default': {
        'ENGINE': 'django.db.backends.sqlite3',
        'NAME': 'db.sqlite3',
    },
    'db1': {
        'ENGINE': 'django.db.backends.mysql',
        'NAME': 'mysql_test_db1',
        'USER': 'root',
        'PASSWORD': 'Se7eN521',
        'HOST': '127.0.0.1',
        'PORT': '3306'
    },
    'db2': {
        'ENGINE': 'django.db.backends.mysql',
        'NAME': 'mysql_test_db2',
        'USER': 'root',
        'PASSWORD': 'Se7eN521',
        'HOST': '127.0.0.1',
        'PORT': '3306'
    }
}

DATABASE_APPS_MAPPING = {
    "db1_app": "db1",   # db1_app 對應(yīng) db1 數(shù)據(jù)庫
    "db2_app": "db2"    # db2_app 對應(yīng) db2 數(shù)據(jù)庫
}

# _*_ coding:utf-8 _*_
# @Time : 2023/4/20 5:37 下午

from django.conf import settings

DATABASE_MAPPING = settings.DATABASE_APPS_MAPPING
print('DATABASE_MAPPING = {}'.format(DATABASE_MAPPING))

class DatabaseAppsRouter(object):

    # 設(shè)置 應(yīng)用app 讀取時數(shù)據(jù)庫的設(shè)置
    def db_for_read(self, model, **hints)if model._meta.app_label in DATABASE_MAPPING:
            return DATABASE_MAPPING[model._meta.app_label]
        return None

    def db_for_write(self, model, **hints):
        if model._meta.app_label in DATABASE_MAPPING:
            return DATABASE_MAPPING[model._meta.app_label]
        return None

    def allow_relation(self, obj1, obj2, **hints):
        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_migrate(self, db, app_label, model_name=None, **hints):
        """
        Make sure that apps only appear in the related database.
        根據(jù)app_label的值只在相應(yīng)的數(shù)據(jù)庫中創(chuàng)建一個表，如果刪除該def或
        不指定過濾條件，則一個Model會在每個數(shù)據(jù)庫里都創(chuàng)建一個表。
        """
        if db in DATABASE_MAPPING.values():return DATABASE_MAPPING.get(app_label) == db
        elif app_label in DATABASE_MAPPING:
            return False
        return None

#test_django為項目名，database_router為路由文件名，DatabaseAppsRouter為路由中創(chuàng)建的類名
DATABASE_ROUTERS = ['django_db_demo.database_router.DatabaseAppsRouter']

from django.db import models

class SqliteModel(models.Model):
    """帳號和用戶關(guān)聯(lián)"""

    sqlite_name = models.CharField(max_length=20)
    class Meta:
        # 當(dāng)前這個 SqliteModel 定義的數(shù)據(jù)庫的表將會創(chuàng)建在test_app 對應(yīng)的default 數(shù)據(jù)庫中
        app_label = "test_app"      # 當(dāng)有多個數(shù)據(jù)庫鏈接的時候，要通過app_label 來區(qū)分這個model對應(yīng)那個數(shù)據(jù)庫
   
class Db1Model(models.Model):
    """帳號和用戶關(guān)聯(lián)"""

    db1_name = models.CharField(max_length=20)
    class Meta:
        # 當(dāng)前這個Db1Model 定義的數(shù)據(jù)庫的表將會創(chuàng)建在 db1_app 對應(yīng)的 db1 數(shù)據(jù)庫中
        app_label = "db1_app"        # 當(dāng)有多個數(shù)據(jù)庫鏈接的時候，要通過app_label 來區(qū)分這個model對應(yīng)那個數(shù)據(jù)庫
       
class Db2Model(models.Model):
    """帳號和用戶關(guān)聯(lián)"""

    db2_name = models.CharField(max_length=20)
    class Meta:
        # 當(dāng)前這個Db2Model 定義的數(shù)據(jù)庫的表將會創(chuàng)建在 db2_app 對應(yīng)的 db1 數(shù)據(jù)庫中
        app_label = "db2_app"       # 當(dāng)有多個數(shù)據(jù)庫鏈接的時候，要通過app_label 來區(qū)分這個model對應(yīng)那個數(shù)據(jù)庫
      

python3 manage.py makemigrations  
python3 manage.py migrate --database=default   # 當(dāng)有多個數(shù)據(jù)庫，需要遷移多次
python3 manage.py migrate --database=db1
python3 manage.py migrate --database=db2