如何访问应用程序目录外的数据库

我想从mySql数据库中获取所有的使用数据。

require_once __DIR__.'/../vendor/autoload.php';
$app = require __DIR__ . '../../bootstrap/app.php';
$app->boot();
$user=new \App\User();
dd(user::all());//get all user details.

Fatal error: Uncaught Error: Call to a member function connection() on null in C:\inetpub\wwwroot\blog2\vendor\laravel\framework\src\Illuminate\Database\Eloquent\Model.php:1138 Stack trace: #0 C:\inetpub\wwwroot\blog2\vendor\laravel\framework\src\Illuminate\Database\Eloquent\Model.php(1104): Illuminate\Database\Eloquent\Model::resolveConnection(NULL) #1 C:\inetpub\wwwroot\blog2\vendor\laravel\framework\src\Illuminate\Database\Eloquent\Model.php(936): Illuminate\Database\Eloquent\Model->getConnection() #2 C:\inetpub\wwwroot\blog2\vendor\laravel\framework\src\Illuminate\Database\Eloquent\Model.php(847): Illuminate\Database\Eloquent\Model->newBaseQueryBuilder() #3 C:\inetpub\wwwroot\blog2\vendor\laravel\framework\src\Illuminate\Database\Eloquent\Model.php(885): Illuminate\Database\Eloquent\Model->newModelQuery() #4 C:\inetpub\wwwroot\blog2\vendor\laravel\framework\src\Illuminate\Database\Eloquent\Model.php(836): Illuminate\Database\Eloquent\Model->newQueryWithoutScopes() #5 C:\inetpub\wwwroot\blog2\vendor\laravel\framework\s in C:\inetpub\wwwroot\blog2\vendor\laravel\framework\src\Illuminate\Database\Eloquent\Model.php on line 1138

我怎样才能得到所有的用户数据。