database design- diagrams I'm trying to derive an Entity Relation diagram from a class diagram. 
In the class diagram, I have a class Player with one to many relationship to another class Payment. In Payment there is no attribute 'paymentID' and 'playerID' is foreign key. Since the same player ('playerID') can make the same payment many times, I thought of adding an attribute 'paymentID' to the Payment table. Is this right? Will I still follow the requirements? I'm new to all these, thank you for any help.
Every table should have a primary key (I really can't think of a reason not to have one). So having a paymentID column to your payment table is definitely a standard design.