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College of Computing and Informatics

Assignment 1

Deadline: Saturday 13/10/2018 @ 23:59

[Total Mark for this Assignment is 6]

Introduction to Database

IT244

Student Details:

Marks: 1

Learning Outcome(s):

Explain database concepts, systems, and architectures.

What is Data-Manipulation Language (DML)? There are four types of access in DML, explain each one.

Ans.

Marks 2

Learning Outcome(s):

Create entity-relationship model, relational model, and write queries.

Assume we have a Library Database consists of the following relations:

author(author_id, first_name, last_name)

author_publication(author_id, publication_id, author_position)

book(book_id, book_title, month, year, editor)

publication(publication_id, title, book_id)

Note: (editor) in book’s relation refers to (author_id) in author’s relation. Some of authors are book editors.

1. Underline the appropriate primary keys/foreign keys in the above relations. (mark: 1)

Ans.

1. Write two relational algebra expressions that retrieve:

• The last names of all authors who are book editors only. (mark: 0.5)

Ans.

• The first name of all authors who are not book editors. (mark: 0.5)

Ans.

Marks 2

Learning Outcome(s):

Create entity-relationship model, relational model, and write SQL queries.

1. Consider that you are asked to design an entity relationship diagram based on the below scenario:

A university consists of a number of departments (id, d_name) and each department offers some courses. A number of modules make up each course. Students enroll their Id, full name, and gender in a particular course and take modules towards the completion of that course. Each module is taught by a lecturer from the appropriate department. (1.5 Marks)

Ans.

1. We can convert any weak entity set to a strong entity set by simply adding appropriate attributes. Why, then do we have weak entity sets? Write about the weak entities for several reasons. (0.5 Mark)

Ans.

Marks 1

Learning Outcome(s):

Design a database starting from the conceptual design to the implementation of database schemas.

Convert the following ER diagrams into relational schemas with the primary key defined for each relation.

Ans.