1. Which of the following are likely to be reasonable entity types in a
typical business system. For those that you do not think are reasonable
entity types, indicate why they do not qualify.
b. Computer sales tax
h. Edit transaction
i. Manufactured part
k. ASCII character
2. Which of the following are likely to be relationships in an ERD and
which are not? Why or why not?
c. Belongs to
f. Sales tax computation
3. For each of the following, suggest a way to identifying an instance.
Which ones are therefore likely to be strong or weak entities?
b. street corner
e. real estate purchase
f. stock holding
h. personal computer
i. super market purchase
k. road sign
4. Draw an ER Diagram to represent the following situation for an airline:
“XYZ airline has three major resources aeroplanes, pilots, and crew
members. Pilots and crew members have respective home bases, to
which they return at the end of an assigned flight. A flight on a particular
day must have an aeroplane, at least one pilot and one or more crew
members attached to it. Each aeroplane has a maintenance base.”
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5. Draw an ER Diagram to describe the following situation for a publisher:
“ABC Press works with several different authors who write the books it
publishes. Some authors have written only one book, while others have
written many; also, some books are co-authored by multiple authors. ABC
also works with multiple printers; each book, though, is printed by only one
printer. An editor as ABC Press works with several authors at a time,
editing and producing their book projects; it is the editors job to turn over
the final camera-ready copy to the printer when the manuscript has been
copyedited and typeset.”
6. Study the following narrative and draw ER Diagrams with cardinality
constraints. Ensure that every entity identifiable.
a. Orders(identified by order_id) are made for parts (identified by
part_no). any quantity of parts can be ordered in an order.
b. Students (identified by student_id) are graded in units( with a
unit-code) in different semesters.
c. Each car (identified by registration number) is on sale at a
particular car yard ( at an address) for a price. Each car yard is
owned be a dealer.
d. Each book (identified by barcode number) barrowed by a
member (identified by borrower_id) is due on a particular date.
e. The date and amounts of all withdrawals and deposits on
accounts (identified by account_no)
f. The distance travelled in kilometres by cars (identified by
registration number) by particular drivers (identified by driver_id)
on various dates.
g. A person starts on a project on a given start date. More than one
person can start on the same project on the same date but a
person can start only once on the same project and cannot start
on more than one project on the same date. A person can work
on more than one project.
h. A delivery (identified by delivery number) may supply many
parts (identified by part number). Each part has one weight
(measured in kilograms) and may come in different colours. For
each part of a certain colour, the quantity delivered is picked
from the quantity on hand.
i. Subjects (identified by subject name) use a number of texts.
Each text has a unique name and can have a number of
authors. An author is identified by their name. Each subject can
be taught a number of semesters and there is one teacher for
each subject each semester.
j. Suppose in case I) different teachers recommend different texts
for the same subject, but not in different semester.
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