COP-5725
PRACTICE EXERCISES
Chapter 5: Queries, Triggers, Constraints
(up to, but not including aggregation)
M. Amanda Crick
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:
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)
1.
Find the pnames of parts for which there is some
supplier.
Exercise 5.2
Solution for (1)
SELECT DISTINCT P.pname
FROM Parts P, Catalog C
WHERE P.pid = C.pid
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)
4.
Find the pnames of parts supplied by Acme Widget
Suppliers and no one else.
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’ )
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)
6.
For each part, find the sname of the supplier who
charges the most for that part.
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)
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)
8.
Find the sids of suppliers who supply a red part and a
green part.
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’
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)
9.
Find the sids of suppliers who supply a red part or a
green part.
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’
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:
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)
1.
Print the names and ages of each employee who
works in both the Hardware department and the
Software department.
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’
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)
3.
Print the name of each employee whose salary
exceeds the budget of all of the departments that
he or she works in.
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)
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)
5.
Find the enames of managers who manage the
departments with the largest budgets.
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))
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)
8.
Find the enames of managers who manage the
departments with the largest budgets.
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 < 5000000
EXCEPT
SELECT M3.sid
FROM Emp M3, Dept D2
WHERE M3.sid = D2.managerid AND
D2.budget <= 5000000)
This is the end of the lecture!
I hope you enjoyed it.