Product ( pid, name, price, category, maker-cid)
Purchase (buyer-ssn, seller-ssn,
store, pid)
Company (cid, name, stock
price, country)
Person(ssn, 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 did not buy French products
Ex #4: Find names of people who bought American products and they live in Seattle.
Ex #5: Find people who bought stuff from Joe or bought products from a company whose stock prices is more than $50.
1. p ssn, name, phne-number, city
(Person ⋈ ssn=buyer-ssn (p buyer-ssn (Purchase ⋈ (s category=”telephony” Product))))
2. p name (Person ⋈ ssn=buyer-ssn (Purchase ⋈ ((p pid, maker-cid
Product) ⋈ maker-cid=cid (p cid (s country=”USA” Company)))))
3. p name ((Person ⋈ ssn=buyer-ssn
(Purchase ⋈ ((p pid, maker-cid
Product) ⋈ maker-cid=cid (p cid (s country=”USA” Company)))))
–
(Person ⋈ ssn=buyer-ssn
(Purchase ⋈ ((p pid, maker-cid
Product) ⋈ maker-cid=cid (p cid (s country=”France” Company))))))
4. p name ((s city=”Seattle” Person) ⋈ ssn=buyer-ssn
(Purchase ⋈ ((p pid, maker-cid
Product) ⋈ maker-cid=cid (p cid (s country=”USA” Company)))))
5. p ssn, name, phne-number, city
(Person ⋈ ssn=buyer-ssn (p buyer-ssn(Purchase ⋈ seller-ssn=ssn (s name=”Joe” Person))))
⋃ p ssn, name,
phne-number, city (Person ⋈ ssn=buyer-ssn
(Purchase ⋈ ((p pid, maker-cid
Product) ⋈ maker-cid=cid (p cid (s stock-price>$50 Company)))))