1. Relational Algebra and SQL
Given relational schema:
Frequent (D, P)
Serves (P, B)
Likes (D, B)
Attributes: P (pub), B (beer), D (drinker)
The pubs that serve a beer that Jefferson likes.
Drinkers that frequent at least one pub that serves “Bud” or “Becks”.
Drinkers that frequent only pubs that serve some beer they like
Drinkers that frequent only pubs that serve no beer they like.

2. 1) Algebra
Solution 1:
Solution 2:
Solution 3:
Solution 4: 16

3. 2) SQL Solution 1: Solution 2: FROM S WHERE b IN (‘Bud”, ‘Becks’))
SELECT p
FROM S, L
WHERE S.b=L.b AND L.d=‘Jefferson’
SELECT d
FROM F
WHERE F.p in (SELECT p
FROM S
WHERE b IN (‘Bud”, ‘Becks’))

4. 2) SQL Solution 3: EXCEPT SELECT d FROM (SELECT * SELECT d,p FROM S, L
FROM F
EXCEPT
SELECT d
FROM (SELECT *
SELECT d,p
FROM S, L
WHERE S.b = L.b)

5. 2) SQL Solution 4: Solution 4 (alternative solution): SELECT d FROM F
EXCEPT
SELECT d
FROM (SELECT *
INTERSECT
SELECT d,p
FROM S, L
WHERE S.b = L.b)
Solution 4 (alternative solution):
SELECT d
FROM F
WHERE (SELECT COUNT (DISTINCT p)
FROM S, L
WHERE F.p=S.p AND S.b=L.b
AND L.d=F.d) = 0