You need a Supply ID primary key in the Supply table with event no and wedding no as foreign keys. The way you have it set up currently, each event/wedding can have only one supply (I'm assuming the...

What is the difference between the lecture entity and the session entity; isn't a lecture just a type of session? Same with practical session and session.

I see you removed the relationship...

This is how I would approach the issue. I would have one table to track the bills, one table to track the people and one table to track the transactions:

Bills (ID, amount, date billed, date due,...

This is my recommendation:

Create one 'user' table that stores, at a minimum, UserId, but could also store name, DOB, etc.

Create one 'Attributes' table that stores all the different...