Hi, @Awais Muhammed Welcome to the Microsoft Q&A platform, thanks for posting the question
As I understand correctly the ask here is how to use Azure API App with MySQL
Unfortunately, there are not any tutorials in API App docs, here is the generic API app to understand how to write code and deploy to the API app You can try checking this doc here,
For this "how can I expose this MySQL database to API so that it is first testable at least in Postman client before moving into Visual Studio IDE?",
--API app can connect to the database using a driver like MySQL .NET connector if building a .NET app. There is no other way today to connect to the database directly without a driver.
you may need to install Azure SDK in that runtime language for doing any management operation on the server such as updating firewall rules, updating the configuration of the server, etc programmatically.
you may not need the SDK if you are using a single database and plan to only connect and query from the API app.
You can also refer to this StackOverflow that shows how to use Xamarin app using the .NET connector for MySQL
I have updated my comments.
I hope this information helps. please let me know if you have any additional questions.
Regards
Geetha