How to design the database tables and relationships

Question

I was creating a system for its purchases and transactions and initially thought the db would needed to be look like this.

https://i.sstatic.net/XIciA.jpg

But after getting into the system

• The products from the suppliers are needed to be bought time to time
• The same product can be get from different suppliers.

So I changed the db to this way.

I'm still figuring out is this the best approach. And also is the product_purchase and order_products tables are many to many tables?

https://i.sstatic.net/QQO5W.jpg

Answer 1

I suggest you to study about entity relationship model and all the phases of a database design (requirements, conceptual, logic, implementation). A wrong database design will influence negatively all the software that will be based on it in terms of performance and architecture.