Question: Consider the following relation:
Order (Product_ID, Product_Name, Customer_ID, Customer_Name, Date, Item_Price, Amount, Total)
OBS: If the same customer sends multiple orders on the same day they are combined. Therefore, we only have one order per customer per day.
Determine all non-trivial functional dependencies of this relation and provide your reasoning.
I do understand what non trivial FD's are. Basically if X -> Y and Y is not a subset of X, then we have an FD. So when it in this questions asks me to write down all of non trivial FD's, i'm uncertain in regards to how many there really are. So i'd like to mention some that i think are non trivial FD's and then i would appreciate some corrections or if someone can add the ones im missing with explanation on why that's a non trivial FD that would be nice too.
product_id -> product_name.. if we know product id we know the product name
product_id -> item_price... if we know product id we also know item price(?)
product_id -> item_price, product_name... if we know product id we know both item price and product name..
product_id, item_price -> product_name... in this one it's unnecessary to have item price, but it's still a non trivial fd i would assume?
Would these be considered valid non trivial FD's? there seems to be endless (almost) combinations.. do need to mention them all? also is product name a primary key? if it is, what does that mean then?