1. COP-5725 Practice Exercises
Chapter 5: Queries, Triggers, Constraints
(up to, but not including aggregation)
M. Amanda Crick

2. Exercise 5.2 Problem Consider the following schema
Suppliers(sid: integer, sname: string, address: string)
Parts(pid: integer, pname: string, color: string)
Catalog(sid: integer, pid: integer, cost: real)
The Catalog relation lists the prices charged for parts by Suppliers. Write the following queries in SQL:

3. Exercise 5.2
Problem
Suppliers(sid: integer, sname: string, address: string)
Parts(pid: integer, pname: string, color: string)
Catalog(sid: integer, pid: integer, cost: real)
Find the pnames of parts for which there is some supplier.

4. Exercise 5.2 Solution for (1) SELECT DISTINCT P.pname
FROM Parts P, Catalog C
WHERE P.pid = C.pid

5. Exercise 5.2
Problem
Suppliers(sid: integer, sname: string, address: string)
Parts(pid: integer, pname: string, color: string)
Catalog(sid: integer, pid: integer, cost: real)
Find the pnames of parts supplied by Acme Widget Suppliers and no one else.

6. Exercise 5.2 Solution for (4) SELECT P.pname
FROM Parts P, Catalog C, Suppliers S
WHERE P.pid = C.pid AND C.sid = S.sid
AND S.sname = ‘Acme Widget Suppliers’
AND NOT EXISTS ( SELECT *
FROM Catalog C1, Suppliers S1
WHERE P.pid = C1.pid AND C1.sid = S1.sid AND
S1.sname <> ‘Acme Widget Suppliers’ )

7. Exercise 5.2
Problem
Suppliers(sid: integer, sname: string, address: string)
Parts(pid: integer, pname: string, color: string)
Catalog(sid: integer, pid: integer, cost: real)
For each part, find the sname of the supplier who charges the most for that part.

8. Exercise 5.2 Solution for (6) SELECT P.pid, S.sname
FROM Parts P, Suppliers S, Catalog C
WHERE C.pid = P.pid
AND C.sid = S.sid
AND C.cost >= ALL (SELECT C1.cost)
FROM Catalog C1
WHERE C1.pid = P.pid)

9. Exercise 5.2
Problem
Suppliers(sid: integer, sname: string, address: string)
Parts(pid: integer, pname: string, color: string)
Catalog(sid: integer, pid: integer, cost: real)
Find the sids of suppliers who supply a red part and a green part.

10. Exercise 5.2 Solution for (8) SELECT DISTINCT C.sid
FROM Catalog C, Parts P
WHERE C.pid = P.pid AND P.color = ‘Red’
INTERSECT
SELECT DISTINCT C1.sid
FROM Catalog C1, Parts P1
WHERE C1.pid = P1.pid AND P1.color = ‘Green’

11. Exercise 5.2
Problem
Suppliers(sid: integer, sname: string, address: string)
Parts(pid: integer, pname: string, color: string)
Catalog(sid: integer, pid: integer, cost: real)
Find the sids of suppliers who supply a red part or a green part.

12. Exercise 5.2 Solution for (9) SELECT DISTINCT C.sid
FROM Catalog C, Parts P
WHERE C.pid = P.pid AND P.color = ‘Red’
UNION
SELECT DISTINCT C1.sid
FROM Catalog C1, Parts P1
WHERE C1.pid = P1.pid AND P1.color = ‘Green’

13. Exercise 5.4
Problem
Consider the following relational schema. An employee can work in more than one department; the pct_time field of the Works relation shows the percentage of time that a given employee works in a given department.
Emp(eid: integer, ename: string, age: integer, salary: real)
Works(eid: integer, did: integer, pct_time: integer)
Dept(did: integer, dname: string, budget: real, managerid: integer)
Write the following queries in SQL:

14. Exercise 5.4
Problem
Emp(eid: integer, ename: string, age: integer, salary: real)
Works(eid: integer, did: integer, pct_time: integer)
Dept(did: integer, dname: string, budget: real, managerid: integer)
Print the names and ages of each employee who works in both the Hardware department and the Software department.

15. Exercise 5.4 Solution for (1) SELECT E.ename, E.age
FROM Emp E, Works W1, Works W2, Dept D1, Dept D2
WHERE E.eid = W1.eid AND W1.did = D1.did AND
D1.dname = ‘Hardware’ AND
E.eid = W2.eid AND W2.did = D2.did AND D2.dname = ‘Software’

16. Exercise 5.4
Problem
Emp(eid: integer, ename: string, age: integer, salary: real)
Works(eid: integer, did: integer, pct_time: integer)
Dept(did: integer, dname: string, budget: real, managerid: integer)
Print the name of each employee whose salary exceeds the budget of all of the departments that he or she works in.

17. Exercise 5.4 Solution for (3) SELECT E.ename FROM Emp E
WHERE E.salary > ALL (SELECT D.budget
FROM Dept D, Works W
WHERE E.eid = W.eid AND D.did = W.did)

18. Exercise 5.4
Problem
Emp(eid: integer, ename: string, age: integer, salary: real)
Works(eid: integer, did: integer, pct_time: integer)
Dept(did: integer, dname: string, budget: real, managerid: integer)
Find the enames of managers who manage the departments with the largest budgets.

19. Exercise 5.4 Solution for (5) SELECT E.ename FROM Emp E
WHERE E.eid IN (SELECT D.managerid
FROM Dept D
WHERE D.budget >= ALL (SELECT D2.budget
FROM Dept D2))

20. Exercise 5.4
Problem
Emp(eid: integer, ename: string, age: integer, salary: real)
Works(eid: integer, did: integer, pct_time: integer)
Dept(did: integer, dname: string, budget: real, managerid: integer)
Find the enames of managers who manage the departments with the largest budgets.

21. Exercise 5.4 Solution for (8) SELECT M.ename FROM Emp M
WHERE M.sid IN (SELECT M2.sid
FROM Emp M2, Dept D
WHERE M2.sid = D.managerid AND D.budget <
EXCEPT
SELECT M3.sid
FROM Emp M3, Dept D2
WHERE M3.sid = D2.managerid AND
D2.budget <= )

22. This is the end of the lecture!
I hope you enjoyed it.