As far as I understand, every instance of Azure Digital Twins Preview brings its own IoT-Hub. A normal Azure IoT-Hub I could query like this (https://docs.microsoft.com/en-us/azure/iot-hub/iot-hub-devguide-query-language):
SELECT * FROM devices
How do I query the built in IoT-Hub of Azure Digital Twins? Or isn't it possible to access this IoT-Hub and I always have to use the Digital Twins REST-API?
The current preview of Azure Digital Twins does not allow you to query the IoT Hub. However, at Microsoft Build, a new version of the preview was announced. This will change the structure of the Digital Twins itself and also allow you to bring your own Azure IoT Hub to integrate with. In the Build Book Of News, it is stated that this preview should come this summer.
As Matthijs van der Veer mentioned, Currently, there is no direct access to the IoT Hub created along with Digital Twins. However, in GA we will have the ability for you to bring your own/directly create & associate your own hub. Yes, you need to use Management API to connect the IotHub.
The new capabilities, which will be available in the summer of 2020, include OPEN Modeling Language, live execution environment, easy integration with Azure IoT Hub and other Azure services, and rich query APIs.
For more updates regarding Azure Digital Twins, please check Azure Updates page.
