I'm designing a database for a careers day registration system. The database has to maintain data for the year of the careers day, registered companies, company contacts, registration details, "products" purchased, and payment information.

The current design I have is as follows:

cada (year)

cada_company (company_id, company_name)

cada_company_contact (company_id, contact_name)
cada_company_registration (company_id, number_of_booths)

cada_participation (year, company_id)

cada_item (item_id, item_name, item_price, item_initial_stock, item_current_stock)

cada_cart (cart_id, company_id)

cada_cart_items (cart_id, item_id, item_price, item_quantity)
cada_cart_payment (cart_id, payment_date, payment_method, payment_amount)

If anybody give me some advice on how I can improve this design, it would be appreciated. Thank you.

Item price might give you some problems the way you have set it up.

I would need more explanation of the business rules before I could recommend anything.