Databases Bachelor IK
December 17, 2003
Instructor: H. Afsarmanesh
University of Amsterdam
FINAL EXAM
1st Repetition
Name:
________________________________________________
Student Number:
________________________________________________
INSTRUCTIONS:
Please think carefully about each question before answering. Quality of answers is
important, not quantity. It is advisable to read the entire exam before starting to answer
any of the questions. Please write all your answers on the exam sheets. Put your name
and student number on the exam sheet. Good Luck!
Question
Points
Question 1
18
Question 2
22
Question 3
15
Question 4
10
Question 5
20
Question 6
15
TOTAL
100
Grade
“Trade” Database description:
The following description is used for two questions. Question 1 is focused on
relational data modeling, while Question 2 is focused on the ER data modeling.
We want to build a “Trade database” to contain information about wholesalers,
retailers, products and the product-orders (for those products that retailers send
orders to wholesalers).
Every wholesaler accepts orders from several retailers, and every retailer sends
orders to several wholesalers.
Furthermore, Every wholesaler offers several products, and every product is
offered by several wholesalers.
Also, every retailer sends orders for several products, and every product can
appear in several orders from retailers.
Detailed characteristics of entities in the database:
 Every seller in the market, being a retailer or wholesaler, has a unique
identifier number in the database, plus its address and phone number.
 Each product has a unique merchandise number in the database, plus its
color, weight, and size.

Each order has a unique order number in the database, plus its date and
status.
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Question 1. (18 points)
a. Draw the ER diagram for the Trade database, indicating all the schema elements.
In this diagram, you can introduce names for some schema elements, when and if
necessary.
b. List all the entity sets.
c. List all the relationship sets.
d. List all sub-classes.
e. List all super-classes.
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Question 2. (18 points)
a.
Sketch a good relational schema for the Trade database to capture all the
information given to you above. This schema must define the information as simple
as possible with minimal logical redundancy.
b. In every relation you defined above, “circle” its primary key in the relation.
c. For every relation list its foreign keys below.
d. Define all functional dependencies that hold in this schema.
e. For every relation, specify if it is in 3rd normal form or not.
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Question 3. (15 points)
This question has 3 sections focused on the DMLs for relational databases:
a.
Specify for each of the following Data Manipulation Languages (DMLs) if the
“duplicate tuples” are by default “kept” or “removed”.

Relational algebra

SQL

QBE
b. Specify the operation/command in the following DMLs, that when used it reverses this
default/automatic treatment of duplicate tuples.
c.

Relational algebra

SQL

QBE
In the following example relation:
CUSTOMER = (CUSTOMER-ID, ACCOUNT-NUMBER, BALANCE)
Give an example “question” (in English) for this relation that if the DML used for writing
this query keeps the duplicate tuples, the results may be wrong.
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The following “employee” database is used for the next 3 questions. Question 4 focuses
on the SQL schema creation and data modification commands. Question 5 focuses on
SQL queries / data retrieval. Question 6 focuses on the QBE queries.
Consider the following relational schema for the employee database.
The primary key is underlined in each relation.
EMPLOYEE (EMPLOYEE-NAME, STREET, CITY)
WORKS (EMPLOYEE-NAME, COMPANY-NAME, SALARY)
COMPANY (COMPANY-NAME, CITY)
MANAGES (EMPLOYEE-NAME, MANAGER-NAME)
Question 4. (10 points)
a.
Give the SQL schema definition for this employee database. Choose and specify an
appropriate domain for each attribute in each of the relations.
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EMPLOYEE (EMPLOYEE-NAME, STREET, CITY)
WORKS (EMPLOYEE-NAME, COMPANY-NAME, SALARY)
COMPANY (COMPANY-NAME, CITY)
MANAGES (EMPLOYEE-NAME, MANAGER-NAME)
b.
Write the SQL data modification command for:
Modifying the database so that Jones now lives in the Newtown city.
c.
Write the SQL data modification command for:
Giving all the employees of the Commerce Bank a 10 percent raise.
Question 5 (20 points)
Construct the following SQL queries for this employee relational database.
a. Find the names of all employees work for the First Bank Corporation.
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b. Find the names, street address, and cities of employees who work for the First Bank.
Corporation, and earn more than $10,000.
c. Find all the employees in the database who live in the same cities and on the same
streets as do their managers.
d. Find all employees who earn more than the average salary of all employees of their
company.
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EMPLOYEE (EMPLOYEE-NAME, STREET, CITY)
WORKS (EMPLOYEE-NAME, COMPANY-NAME, SALARY)
COMPANY (COMPANY-NAME, CITY)
MANAGES (EMPLOYEE-NAME, MANAGER-NAME)
Question 6. (15 points)
Construct the following QBE queries for the employee relational database.
a. Find the names, street address, and cities of employees who work for the First Bank
Corporation, and earn more than $10,000.
b. Find all the employees in the database who live in the same cities and on the same
streets as do their managers.
c. Find all employees who live in the city where the company for which they work is
located.
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