Name:___________________
UNIVERSITY OF CALGARY
Lab section: ________
FACULTY OF SCIENCE
MIDTERM EXAMINATION
CPSC 471
Closed book exam
Total 100 points
Page 1 of 9
CPSC 471
University of Calgary
Department of Computer Science
CPSC 471 Database Management Systems
ID:
Midterm Exam
Before you start the exam, please note that:
1. Write you ID and name before your start
2. There are 8 pages with a total of 5 questions in this exam.
3. Read the five exam questions carefully.
4. The points for the problems are marked below.
5. Answer all the questions in the space provided.
6. You can use the back side of the page, if necessary
7. The problems are not necessarily arranged in the order of their difficulties.
8. You may do the ones that you feel comfortable first.
9. Partial solutions will be accepted for partial credits.
Question
Total
Points
1
25
2
20
3
25
4
20
5
10
100
Result
Page 2 of 9
CPSC 471
Q1. Consider the following relations that contain information about countries, cities, streets and houses. For each
country, name, area and population are kept; and its neighbor countries are stored in Border; note that if
(Canada, USA) is in Border then (USA, Canada) is not in Border. For each city, we keep city name, country
name, area and population of the city. For each street, we keep street number, city name and length of the
street. For each house we keep house number, number of rooms, owner name and street number.
Country(name, area, population)
Border(country_name1, country_name2)
City(city_name, country_name, area, population)
Street(stno, cityn, length)
House(hno, #rooms, stno, owner-name)
Code the following queries using Relational Algebra:
(5) a) Find street number of the longest street in each city in Canada?
Longest (city, max_ length) =[ cityn ℑmax(length) ( street
Re sult = ∏ ( Longest
stno
><
city = cityn ∧ max_ length = length
><
city _ name=cityn
(
σ
country _ name= 'Canada '
(city))]
Street )
(5) b) Find names of persons who own at least one house in each city in Canada?
R(cityn) =
S=
σ
∏ (
city _ name country _ name = 'Canada '
∏
(City ))
( Street * House)
cityn ,owner _ name
Re sult = S ÷ R
(5) c) Find names of persons who own at least one house outside USA?
Re sult =
∏
(
σ
owner _ name country _ name≠ 'USA'
(City )
∞
city _ name=cityn
( Street * House))
Page 3 of 9
CPSC 471
Country(name, area, population)
City(city_name, country_name, area, population)
House(hno, #rooms, stno, owner-name)
Border(country_name1, country_name2)
Street(stno, cityn, length)
Code the following queries using SQL:
(5) d) Find names of countries that have border with Germany?
(SELECT country-name1 FROM border WHERE countryname2=’Canada’)
UNION
(SELECT country-name2 FROM border WHERE country-name1=’Canada’);
(5) e) Find names of persons who own at least one house in Canada?
SELECT
FROM
WHERE
h.owner_name
(City AS c JOIN Street AS s on c.city_name=s.cityn NATURAL JOIN
House as h)
c.country_name=’Canada’;
Page 4 of 9
CPSC 471
Q2. Consider the following relations that contain information about books distributed by publishers to schools. A
book may be published by several publishers and distributed to different schools. Here, pname and sname
stand for publisher name and school name, respectively.
Publisher(name, phone, city)
Book(ISBN, title, color, #pages)
School(name, phone, city, director)
Distribute(pname, sname, ISBN, quantity)
Code the following two queries using SQL:
(5) a) Find names and cities of publishers distributing red books to at least one school not located
in Calgary?
SELECT
FROM
WHERE
p.name, p.city
(Publisher AS p JOIN Distribute AS d ON p.name=d.pname
JOIN School as s ON d.sname=s.name JOIN Book as b ON d.ISBN=b.ISBN)
b.color=’red’ AND s.city<>’Calgary’;
(5) b) Find directors of the schools located in Paris and receiving books from publishers located in
London?
SELECT
FROM
WHERE
s.director
(Publisher AS p JOIN Distribute AS d ON p.name=d.pname
JOIN School as s ON d.sname=s.name)
s.city=’Paris’ AND p.city=’London’;
Page 5 of 9
CPSC 471
Publisher(name, phone, city)
Book(ISBN, title, color, #pages)
School(name, phone, city, director)
Distribute(pname, sname, ISBN, quantity)
Code the following query using Relational Algebra:
(5) c) Find names of schools receiving books from publishers located in Roma and distributing
books to at least one school located in Toronto?
P=
∏
σ
((
Publisher . name
∏
Re sult =
∞
( Publisher )
(P
Distribute. sname
( Distribute ))
Publisher .name = Distribute . pname
city = ' Roma '
∞
∞
(
σ
Distribute . sname = School . name city = 'Toronto '
Distribute)
P .name= Distribute. pname
(5) d) Find the name and total quantity of each book distributed only to all the schools in Calgary?
S ( sname ) =
∏( σ
name
R=
∏
( School ))
city = 'Ca lg ary '
( Distribute )
ISBN , sname
T = R÷S
Q = T − ∏ ((T * Distribute)
ISBN
∞
(
σ
School ))
Distribute. sname= School .name city ≠ 'Ca lg ary '
Re sult (Title, Total )= title ℑsum ( quantity ) (Q * Distribute * Book )
( School )))
CPSC 471
Q3. Consider the following ER diagram, derive the corresponding relational schema.
OWNER ownerId
CORPORATION Name Address Phone
PERSON Ssn Address Phone
EMPLOYEE Ssn Salary
PILOT
Name
ownerId
ownerId
Shift
Ssn Lic_Num Restr
PLANE_TYPE Model Capacity Weight
AIRPLANE Reg# Model
Number
HANGAR Number Capacity Location
SERVICE Reg# Date
OWNS ownerId Reg#
Workcode Hours
Pdate
WORKS_ON Ssn
Model
Ssn
Model
FLIES
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Page 7 of 9
CPSC 471
MAINTAIN
Ssn
Reg#
Date
Workcode
Q4. You have been hired by COMSEL as a database designer. Their problem has been defined as follows and you are
asked to draw the corresponding extended ER diagram, specifying your reasonable assumptions when necessary.
COMSEL is running a business selling computer services. Services are classified into internet service and computing
service. Internet service has a bandwidth and IP address. Computing service has MAC address, memory size and
processor power. A user may ask for an internet service for unlimited period or may specify the period. Also a user
has to specify the maximum memory size required for the computing service. COMSEL has representatives in
different locations in Canada. A representative has name, phone, and technicians. A technician has name and
specialization. A technician uses and keeps the amount of certain material in providing service to a user. A material
has a name, cost, and supplier. It is the duty of each representative to keep track of the amount of material in the stock
and to order from the supplier by specifying the date of order and the quantity. A supplier has name, location and
phone. Each order leads to delivery in certain quantity and on certain date.
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CPSC 471
Memory size
bandwidth
MAC address
IP address
Processor
power
Internet
service
Computing
Service
period
use
Ask for
max memory
User
name
location
supplier
Order
amount
phone
delivery date
Order date
Supply
order
name
delivery
amount
material
use
name
amount
phone
technician
location
cost
Representative
name
Work for
specialization
Page 9 of 9
CPSC 471
Q5. Consider relation R (A, B, C, D, E), which has two candidate keys: AB and AD
List in the table below five valid tuples of R in a way that minimizes the total number of values in
the five tuples, that is,
Minimize [ number of values(A) + number of values(B) + number of values(C)
+ number of values(D) + number of values(E)];
Use symbols like a1, a2, …, b1, b2, …,
A, B, C, D, and E, respectively.
R
A
c1, c2, …,
B
d1, d2, …., and
C
D
e1, e2, … as values for
E
a1
b1
c1
d1
e1
a1
b2
c1
d2
e1
a2
b1
c1
d1
e1
a2
b2
c1
d2
e1
a3
b1
c1
d1
e1
And another solution could be A= a1, a2,a3,a4,a5 and each of the rest
has one single value.
Both solutions lead to using 9 values