Hi @sedatyildiz as you have read above, my tutorial is about Flask Implementation with SQL Alchemy & PostgreSQL. But this article only explain how to use flask in minimalism way. From my tutorial you can find different way to use Flask by connecting with postgreSQL so you can create and read database.
We can create user.id, user.username & user.email to postgreSQL database like this:

and show the database to your browser like this:

so please can you tell me where is the duplication i have made?