Write the following assertions. The database schema is from the "PC" example: Product(maker, model, type) PC(model, speed, ram, hd, price) Laptop(model, speed, ram, hd, screen, price) Printer(model, color, type, price

a) No manufacturer of PC's may also make laptops. 7.4. ASSERTIONS 331 Comparison of Constraints The following table lists the principal differences among attribute-based checks, tuple-based checks, and assertions Where Type of Constraint Declared Attribute With based CHECK attribute When Activated n insertion to relation or attribute update to Hold? Not subqueries Elemento Not i subqueries n insertion based CHECK relation scha to relation or tuple update On any change to Yes relation AssertionE Elemento database schema any mentioned b) A manufacturer of a PC must also make a laptop with at least as great a c) If a laptop has a larger main memory than a PC, then the laptop must d) If the relation Product mentions a model and its type, then this model processor speed. also have a higher price than the PC must appear in the relation appropriate to that type