If you are the sysadmin or db_owner, you can create ER diagram by using SSMS Database Diagram Designer by referencing below:
Create a New Database Diagram - Visual Database Tools | Microsoft Learn
Understand Database Diagram Ownership - Visual Database Tools | Microsoft Learn
Set Up Database Diagram Designer - Visual Database Tools | Microsoft Learn
But if you are a SQL developer, mostly you are not a member of the db_owner role nor sysadmin, and then you will not pass the checking as illustrated below:
Also, SQL Azure Databases do not support diagrams in the same way 'normal' on premise SQL Servers do, so you should look at workarounds or third-party tools. In this blogpost, I will show you a free third-party tool that can be used to create ER diagrams. DBeaver Community is a free and open-source universal database tool for developers and database administrators. DBeaver ER diagram designer doesn't require database owner permission, as the ER diagram being created by DBeaver will be saved as a .erd file in your desktop (rather than in the database that SSMS database diagrams do). Below screenshot shows a DBeaver ER diagram:
Creating ER diagram in DBeaver is intuitive, you will find it is much easier than SSMS.
