ICS 324 – 03 (081)
Final Exam
1 of 10
King Fahd University of Petroleum and Minerals
College of Computer Sciences and Engineering
Department of Information and Computer Science
First Semester 2008 - 2009 (081)
ICS 324 Database Systems
Section 03
Final Exam Solution
Weight: 25 %
Maximum Points: 100
Time: 07:00 – 09:00 pm
Place: 24 - 120
Student #: ______________
Student Name: ________________________________
Problem Problem Problem Problem Problem Problem Problem
1
2
3
4
5
6
7
30
15
10
15
10
10
10
TOTAL
100
NOTES:
 To make your answers more meaningful, write your assumptions, if any, as part of your
answers.
 Use the time to write the answers only for what is required in the problem. Don’t waste
time in writing which is not required
04 February 2009
ICS 324 – 03 (081)
Final Exam
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Problem 1 [30 points] Answer all the following short questions. Each question is for 2 points.
1.1 Define the term “data” as precisely as you can.
Data are the known facts that can be recorded and have an implicit meaning.
1.2
What is the difference between “data” and “information”
Information is the processed and unambiguously interpretable form/representation
of data.
1.3
What is the difference between “database system” and “database”
Database is a collection of related data whereas a database System is the DBMS
software, the database, and the software programs that are executed to transform
the data from the database to information.
1.4
1.5
What is meta-data? Give an example.
Meta-data is the DBMS catalog that stores the description of a particular database. It
includes the table names, attribute names, , types, and constraints.
What is program-data independence?
program-data independence is the insulation between programs and data that
allows changes in data structures and storage organization without having to
change the DBMS access programs.
ICS 324 – 03 (081)
1.6
Final Exam
3 of 10
List four tasks (responsibilities) of a database administrator.
DBA is responsible for
 Authorizing access to the database
 Coordinating and monitoring its use
 Acquiring software and hardware resources
 Controlling its use
 Monitoring efficiency of operations.
1.7
Define data redundancy. You can support your answer with an example.
Data redundancy is storing a data item more than once in the same database. For
example, name of student may appear in transcript record, registration notice
record. Etc.
1.8
Data redundancy leads to many problems. Describe one such problem.
Keeping the redundant data consistent is an important issue. It may be updated in
one place but not in others.
1.9
Illustrate data integrity with a simple example.
A student number at KFUPM must be unique. Now whenever a new student
number is inserted into the database it must be checked by the DBMS to be unique
as a part of the insert operation.
1.10 A data model is a collection of concepts that can be used to describe the structure of a
database. Just list four concepts that are used to describe the data in relational data model.
Data modeling concepts in relational data model are
 Attribute
 Domain
 Relation
 Primary key
 Foreign key
ICS 324 – 03 (081)
Final Exam
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1.11 A database should always be in a valid state. What does this mean?
A valid state of a database implies that each data value in the database satisfies
the relevant integrity constraints.
1.12 Illustrate the difference between a relation schema and relation state with a simple example.
R(A, B, C) is a relation schema and { <a1, b1, c1>, <a2, b2, c2>} is a relation state.
1.13 Describe the mathematical statement
r(R)  dom(A1) x dom(A2) x dom(A3) in words.
Relation state r of a relation R is a subset of the cartesian product of domains of
A1, A2, and A3.
1.14 List two characteristics of relation in relational data model.
 All values are considered atomic (indivisible).
 Each value in a tuple must be from the domain of the attribute for that
column
 Attributes in a relation schema R (and of values within each tuple) are
ordered
 The tuples are not considered to be ordered, even though they appear to be
in the tabular form.
1.15 Two main relational model constraints are domain constraints and key constraints. In a
create table statement an attribute is defined as Dno INT NOT NULL,
Describe the domain constraints of attribute Dno as specified in the statement.
The domain constraint of Dno has been specified by the type INT which implies that
all integer numbers from -  to +  are the valid values for the attribute Dno. Of
course  in computer storage is limited by the maximum value that can be stored in
the assigned space (1 byte, 2 byte, or 4 bytes) for integer numbers. However the
value cannot be NULL.
ICS 324 – 03 (081)
Final Exam
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Problem 2 [15 points] (Functional Dependencies and Normalization)
(a) [3+2 points] Define second normal form (2NF) and illustrate with an example.
(b) [10 points] Consider the following relation schema and the functional dependencies:
CAR-SALE (Car#, Date-sold, Salesman#, Commission, Discount)
Primary key: Car#, Salesman#
Functional dependencies:
(fd1) Salesman# → Commission
(fd2) Date-sold → Discount
(b-1) [2 points] Is the given relation schema in 1NF? Explain your answer.
(b-2) [2 points] Is the given relation schema in 2NF? Explain your answer.
(b-3) [2 points] Is the given relation schema in 3NF? Explain your answer.
(b-4) [4 points] If in your opinion the given relation schema is not in 3NF then transform it
into a set of relation schemas such that each resulting relation schema is in 3NF.
Solution
(a) A relation schema R is in second normal form (2NF) if every non-prime attribute
A in R is fully functionally dependent on the primary key
(b)
(b-1) The given relation schema is in 1NF because every attribute is atomic.
(b-2) The given relation schema is not in 2NF because
Salesman# → Commission
defines that Commission is functionally dependent on Salesman# which is
part of the primary key.
(b-3) The given relation schema is not in 3NF because it is not in 2NF
(b-4)
CAR-SALE (Car#, Date-sold, Salesman#, Commission, Discount)
Dividing the relation schema into two relations
CAR-SALE-1 (Car#, Date-sold, Salesman#, Discount)
CAR-SALE-2(Salesman#, Commission)
CAR-Sale-1 is not in 3NF due to transitivity; Car# → Date-sold and
Date-sold → Discount.
Therefore subdividing the CAR-SALE-1 into two relations gives the following
relation schemas where each relation is in 3NF.
CAR-SALE-1-A (Car#, Date-sold, Salesman#)
CAR-SALE-1-B (Date-sold, Discount)
CAR-SALE-2(Salesman#, Commission)
ICS 324 – 03 (081)
Final Exam
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Problem 3 [10 points] (Practical Database Design Methodology)
(a) [4 points] In your understanding, what is the relationship between an information system and a
database system?
(b) [6 points] What are the six phases of database design? Describe each phase briefly.
SOLUTION
(a) A database system provides raw data for an information system
(b)
ICS 324 – 03 (081)
Final Exam
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Problem 4 [15 points] (Index Structures for Files and Physical Database Design)
(a) [5 points] What are the differences between primary indexes and clustering indexes?
(b) [5 points] Why can we have at most one primary index or clustering index on a file, but
several secondary indexes?
(c) [5 points] Creating an index on a relation attribute can improve its access but at the same time
introduces an overhead to maintain the index. Under what circumstances the overhead is
justified. Explain.
ICS 324 – 03 (081)
Final Exam
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Problem 5 [10 points] (Query Processing)
(a) [4 points] Describe or draw a diagram to show the typical steps involved in processing a query
written in a high-level language like SQL.
(b) [6 points] Translate the following SQL query into an equivalent relational algebra expression
and then represent as a query tree.
SELECT
FNAME, LNAME, ADDRESS
FROM
EMPLOYEE
WHERE
DNO IN
( SELECT DNUMBER
FROM
DEPARTMENT
WHERE DNAME='Research' );
ICS 324 – 03 (081)
Final Exam
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Problem 6 [10 points] (Transaction Processing Concepts)
(a) [5 points] Illustrate the temporary update problem with an example. (Please note that a simple
diagram without an appropriate explanation is not a sufficient answer)
(b) [5 points] The desirable properties of a transaction are atomicity, consistency preservation,
isolation, and durability. Explain what atomicity and isolation mean.
ICS 324 – 03 (081)
Final Exam
10 of 10
Problem 7 [10 points] (Concurrency Control Techniques)
(a) [4 points] what is a lock? What is the basic two-phase locking (2PL) protocol?
(b) [6 points] Below find a schedule S of two transaction T1 and T2 that exhibit the lost-update
problem. Use locking and the 2PL to rewrite the schedule S as another schedule S’ that does
not have this problem. Verify your answer by filling the column balx in the two schedules S
and S’.
S’
S
Time
t1
T1
T2
begin_transaction
balx
550
Time
t1
T1
T2
begin_transaction
balx
550
t2
begin_transaction
read (balx)
550
t2
begin_transaction
write_lock (balx)
550
t3
read (balx)
balx = balx + 100
550
t3
write_lock (balx)
read (balx)
550
t4
balx = balx - 50
write (balx)
650
t4
wait
balx = balx + 100
550
t5
write (balx)
committ
500
t5
wait
write (balx)
650
t6
committ
500
t6
wait
Committ/
unlock (balx)
650
t7
read (balx)
650
t8
balx = balx - 50
650
t9
write (balx)
600
t10
Committ/
unlock (balx)
600