CODEWITHSUNDEEP
sql-serverdatabase
user355002
user355002

Reputation: 871

Question about database

I have problem with two parts of database diagram and I need your guidance:) database has a lot of tables that one of them is about Employee ,the other is about Customer and ... ! I have problem with two tables (Product and OrderDetail) my Product table has 3 columns (ProductID,Name,Cost) and the Other table is OrderDetail that has these columns(OrderDetailID,Cost,Quantity) I have not created this database myself I have found it like a sample database in the internet but I have problem about these two Cost which is in OrderDetail and Product tables ,what is the difference between these Cost? they are the same or not? thanks

EDITED: sorry all I had a mistake ,the ID for the ordeDetail table is the composite of primary key of Product table and Order table which is Product ID and OrderID and the OrdeDeatil table is a weak entity. SO OrderDeatil((ProductID,OrderID),Cost,Quantity)

Upvotes: 1

Views: 101

Answers (2)

Daniel Vassallo
Daniel Vassallo

Reputation: 344251

I suppost that the cost in the products table is the current price of the product. On the other hand, the cost in the order details table is the price that was paid for the product for that particular order.

Product prices can go up or down, or discounts might have been given for particular orders. The field in the order details table would store this information.

UPDATE: Further to your updated question, that makes sense. It implies that each order can only list the same product once. The order details table is storing how many items of that product were ordered (quantity) and I would say that cost is the price paid for one item. It could be the total (price * quantity) but that's not a common for such table structures.

Upvotes: 2

Stephen
Stephen

Reputation: 6087

Without knowing exactly what this database is meant to capture, I couldn't say for sure, but as a rough guess I would expect that the Product tables Cost column is the cost for a single unit of that product, and the OrderDetail tables Cost column is the cost for an order of some quantity of 'something' - most likely a certain quantity of a product. Note as an interesting aside that there is nothing linking the OrderDetail table to the Product table - if these two tables are meant to be linked you would normally expect a Foreign Key in the OrderDetail table linking it to the Product table. At the moment, there is no way to match OrderDetails to Products.

Upvotes: 1

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