Hi @Coby Lin ,
Welcome to Microsoft Q&A!
I tested on my side and could reproduce the issue. I suppose it is designed like this.
The table designer is not available for Microsoft Azure SQL Data Warehouse.
If you have any feedback about the feature, you can directly report it to product team by selecting “Help” menu > Send Feedback. Thanks for your understanding!
Sincerely,
Anna
If the answer is the right solution, please click "Accept Answer" and kindly upvote it. If you have extra questions about this answer, please click "Comment".
Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.