Database

Pg. 02

Question Four

Assignment #1

Deadline: Tuesday 29/09/2020 @ 11:59
[Total Marks for this Assignment are 5]

Introduction to Database

IT244

College of Computing and Informatics

Question One
1.5 Marks

Learning Outcome(s):
Create entity-relationship model, relational model, and write SQL queries

Consider the below schema for a library database and write relational algebra expressions for the following queries
1. Author (authorname, citizenship, birthyear)
2. Book (isbn, title, authorname)
3. Topic (isbn, subject)
4. Branch (libname, city)
5. Instock (isbn, libname, quantity)

1. Give all authors’ names born after 1940. [0.25 Point]
2. Give the names of libraries in Sydney. [0.25 Point]
3. Give the city/cities and “isbn” where each book is held. [0.25 Point]
4. Give the title of each book on the topic of either alcohol or drugs. [0.25 Point]
5. Give the title and author of each book of which at least two copies are held in a branch located in Melbourne. [0.50 Point]

Question Two
1 Mark

Learning Outcome(s):
Explain database concepts, systems, and architectures

What is the different between the database schema and the database instance? Give an example for each. The answer should be in your own words.
Question Three
1 Mark

Learning Outcome(s):
Design a database starting from the conceptual design to the implementation of database schemas

Name at least three tables that might be used to store information in the following systems:
a. An e-commerce system such as Amazon. [0.25 Point]
b. A social media system such as Twitter. [0.25 Point]
c. A health care system. [0.25 Point]
d. A university system. [0.25 Point]

Question Four
1.5 Marks

Learning Outcome(s):
Create entity-relationship model, relational model, and write SQL queries

Given the relation below named Contact_Info, answer the following questions:

SSN

Name

Phone

Email

Age

234-356

Sara Fahad

340-675-9876

sara@gmail.com

22

673-980

Mohammad Ahmed

234-896-2567

Moh_3@gmail.com

28

129-678

Waad Saud

280-986-8736

Wad2@hotmail.com

31

a. What is the relational schema of the relation Contact_Info? [0.25 Point]
b. What is the degree of the giving relation? [0.25 Point]
c. Is the column Name an atomic attribute/value? If no, justify your answer? [0.25 Point]

d. What are the outputs of the given operations?
1. (Contact_Info) [0.50 Point]
2. (Contact_Info) [0.25 Point]