Actually in update you want a key that matches one that is already used. Because you are updating, not inserting.
You need the key to match one that exists so you know which record to update.
So there is no such thing as a DuplicateKeyException in update.
You could use the customers Social Security number.
Originally posted by Chan Huan:
I got a same assignment. I think the confusion is what is key. through having analysed the instruction and business model, the key may be consist of name and location field.
Originally posted by Larry Lee:
TQ, I'm not quite agree with it.
I think a hotel with two same room is possible.
Yes, a room number is the best identity, but without it, a room can still be booked, when a customer comes, the waiter takes him to one of these rooms randomly. Looks strange, but possible.