IT360 Lab 4: Normalization
DUE: February 28, 2013, 2359 (paper copy BEFORE start of lab next
day)
Some of the most difficult decisions that you face as a database developer are what tables
to create and what columns to place in each table, as well as how to relate the tables that
you create. Normalization is the process of applying a series of rules to ensure that your
database achieves optimal structure. Normal forms are a progression of these rules. Each
successive normal form achieves a better database design than the previous form did.
Although we discussed several levels of normal forms, this lab focuses on 1st Normal
Form (1NF), and Boyce-Codd Normal Form (BCNF). If you do not understand functional
dependencies, then review the discussion on functional dependencies on the slides and
your notes.
1. Functional Dependencies:
Consider the following relation R with attributes A, B, and C, with 4 rows in it:
A B C
1 3 2
1 4 2
1 5 2
2 6 2
For each of the following functional dependency, specify whether the dependency is true
or false for the specific instance of the table given above:
True/ False
A→B
_________
A→C
_________
B→A
_________
B→C
_________
C→A
_________
C→B
_________
(A,B) → C
_________
(A,C) → B
_________
(B,C) → A
_________
2: 1st Normal Form (1NF)
Consider the Students table, with the primary key underlined, and the following data:
Students:
Alpha
100111
092244
113221
090112
Name
John Doe
Matt Smith
Melinda Black
Tom Johnson
Email
doe@usna.edu
smith@usna.edu
black@usna.edu
Johnson@usna.edu
Courses
NN204, SI204, IT221
SM223, EE301
SI204
NN204, SI204, IT221
StudentGrades
C,B,B
A,A
B
A,C,B
a) Is the Students table in 1NF? Why?
b) If the Students table is not in 1NF, redesign the table such that the resulting tables
are in 1NF. For each of the resulting tables, give the table name, column names,
primary keys, and foreign keys. Write a few rows in each of the new tables, based
on the rows in the initial table. Hint: remember the Enroll table that we used in
class while learning SQL
3. Functional Dependncies and BCNF
Consider the following relational schema:
StudentCourses(studentID, studentName, courseID, profID, profOffice)
Each row in table StudentCourses encodes the fact that the student with the given ID
and name took the given course from the professor with the given ID and office.
Assume that students have unique IDs but not necessarily unique names, and
professors have unique IDs but not necessarily unique offices. Each student has only
one name; each professor has only one office.
a) Specify the functional dependencies for table StudentCourses that encodes the
assumptions described above and no additional assumptions.
b) Specify a possible primary key for the StudentCourses table, based on the stated
assumptions.
c) Give one example of a deletion anomaly in the StudentCourses table.
d) Is StudentCourses in Boyce-Codd Normal Form (BCNF)? Why?
e) If StudentCourses is not in BCNF, decompose StudentCourses such that resulting
tables are in BCNF. For each of the resulting tables, give the table name, column names,
primary keys, and foreign keys. (no need to write the actual data in the resulting tables)
4: SQL
Given the following tables:
ITEM(ItemID, Description, PurchaseDate, Store, City, Quantity, LocalCurrencyAmt,
ExchangeRate)
SHIPMENT(ShipmentID, ShipperName, ShipperInvoiceNumber, DepartureDate,
ArrivalDate, InsuredValue)
SHIPMENT_ITEM(ShipmentID, ShipmentItemNb, ItemID, Value)
Write the ANSI SQL query to find the ItemID and Description for the items with the
lowest shipped Value.
5: (Extra credit) Boyce-Codd Normal Form (BCNF)
Below is the Rentals table created for the "Movies On-demand" division of CamCast.
Rentals:
RentalID
1
Title
Die Hard III
CustomerID
1111
RentalDate
3/3/2012
2
1111
4
The last
man
standing
Wedding
Crashers
Dodgeball
5
6
3
MovieCategory
Old
Price
$4.25
3/3/2012
Director
John
McTiernan
Walter Hill
Old
$4.25
1111
3/3/2012
David Dobkin
New
$5.50
1222
3/4/2012
New
$5.50
Die Hard III
1222
3/4/2012
Old
$4.25
As good as
1332
1/7/2013
Rawson
Marshall
Thurber
John
McTiernan
James
Old
$4.25
7
it gets
Forest
Gump
1111
1/7/2013
Brooks
Robert
Zemeckis
Old
$4.25
The primary key of the Rentals table is RentalID.
d) Explain (English) the conditions under which the following functional
dependency is true:
RentalID -->CustomerID
e) Based on the sample data on the table, is the functional dependency
RentalID --> CustomerID true?
f) Explain the conditions under which the following functional dependency is true:
Director --> Title
g) Based on the sample data on the table, is the functional dependency
Director --> Title true?
h) Based on your general knowledge of movies and rentals, is the functional
dependency Director --> Title true?
i) Write a functional dependency that expresses the fact that all movies in a given
category have the same price.
j) We discussed insertion anomalies, deletion anomalies and update anomalies as
examples of problems that can appear in tables that are not normalized. The
following is an example of an insertion anomaly in the Rentals table: if we want
to create a new category of movies, “Must See”, there is no way to store the price
of this type of movie in the database, until someone rents a movie in this category,
and the rental information is recorded into the Rentals table. Give one example of
a deletion anomaly in the Rentals table.
k) State what you believe are reasonable functional dependencies for the Rentals
table for a Movies On-demand business (include the functional dependencies
from points a) to f) that you believe are/should be true).
l) Given your answer above, decompose the Rentals table such that the resulting
tables are in BCNF. For each of the resulting tables, give the table name, column
names, primary keys, and foreign keys. (no need to write the actual data in the
resulting tables)
6 (Extra credit): 4th Normal Form (4NF)
Do some research (internet, textbook, slides) to learn about multivalued dependencies
and 4NF.
Suppose we have the following Courses table with columns CourseID, Instructor, Book
that stores the courses, the instructor teaching the course, and the recommended books for
the course. The book(s) recommended for a course does not depend on the teacher
teaching the course, just on the course. Here is an example of instantiation for this table:
Courses:
CourseID Instructor
Book
IT360
J. Jones
Kroenke
IT360
J. Jones
Welling
IT360
Burke
Kroenke
IT360
Burke
Welling
SI440
J. Jones
Kroenke
SI440
J. Jones
Ramakrishnan
SI440
J. Jones
Stonebraker
a) Give an example of a multivalued dependency in the Courses table.
b) Is the Courses table in 4NF? If answer to yes, say why. If not, decompose the table
such that the resulting tables are in 4th normal form. For each of the resulting tables,
give the table name, column names, primary keys, and foreign keys.
Turn in paper copies (due before start of lab on March 1, 2013):
Electronic (NOT Required for this lab):
1. Upload the yourlastname_yourfirstname_lab7.doc file containing all answers
including the SQL question to Lab 7 assignment on Blackboard.
Hard-copies:
1. The completed assignment coversheet. Your comments will help us improve the
course.
2.
A hard copy of your answers for each question.