SELF-ASSESSMENT Next: Lesson 3 → Review Questions How does a conceptual model differ from a logical and physical model? Why are the current price of an item and the purchase price stored separately? 1 5 Why doesn't a unique ID guarantee that there are no duplicates? What needs to be determined before setting up a submeter? 2 6 When does a connection acquire its own attributes? How does a reference to an object from another service differ from a foreign key? 3 7 How does a 2NF violation differ from a 3NF violation? 4 ← Lesson Plan