需要帮助将表格标准化为 3NF？

Question

I want to normalize the table So far i have done this:

is it my 3Nf correct?

Order(orderNo,orderDate,customerId)

Customer(customerId,customerName,customerCurrentAddress,customerPermanentAddress)

Product(productId,productName,Qty,categoryId)

Category(categoryId,categoryName)

Sub-Category(subCatId,subCatName,categoryId)

Given table here: https://drive.google.com/file/d/1F7cQjjxz9rnY6RHaGtZXuwVGFEHBVgNo/view

Answer 1

Your unnormalized table contain a Qty field which creates ambiguity. Is it product quantity or quntity of order?

Answer 2

You have to make a junction table between Order and Product in order to keep track of orders that contain more than one product.

Order(orderNo,orderDate,customerId)

Order_Details(orderNo,productId,Qty)

Customer(customerId,customerName,customerCurrentAddress,customerPermanentAddress)

Product(productId,productName,Qty,categoryId)

Category(categoryId,categoryName)

Sub-Category(subCatId,subCatName,categoryId)

Base on the definition from Wiki : a table is in 2NF if it is in 1NF and no non-prime attribute is dependent on any proper subset of any candidate key of the table . Most of your tables only have 2 columns, so they satisfied this. For Customer(customerId,customerName,customerCurrentAddress,customerPermanentAddress) , the candidate key is customerId , and the other columns completely depend on the whole candidate key, then it's OK.

For 3NF, Wiki said: all the attributes in a table are determined only by the candidate keys of that table and not by any non-prime attributes . As you see, your tables are all satisfied.