Product (pname, price, category, manufacturer)
Purchase (buyer, seller,
store, product)
Company (cname, stock price,
country)
Person(per-name, phone number,
city)
Ex #1: Find people who bought
telephony products.
Ex #2: Find names of people who
bought American products
Ex #3: Find names of people who
bought American products and they
live in Seattle.
Ex #4: Find people who have
both bought and sold something.
Ex #5: Find people who bought stuff from Joe or
bought products
from a company whose stock prices
is more than $50.