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(comp231)[2008](s)mid~PPSpider^sol_10181.pdf
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HONG KONG UNIVERSITY OF SCIENCE & TECHNOLOGY
COMP231: Database Management Systems
Spring Semester, 2008
Mid-term Examination
April 2, 2008 19:30 C 20:40

Name: ___________________ Student Number: ______________________

Email: ___________________ Lab Section Number:____________________




















Questions
Marks
Scores

1
10


2
25


3
30


4
35


Total
100




Instructions:

1. This examination paper consists of 7 pages and 4 questions

2. Please write your name, student ID and Email on this page.

3. For each subsequent page, please write your student ID at the top of the page in the space provided.

4. Please answer all the questions within the space provided on the examination paper. You may use the back of the pages for your rough work and afterwards drawn a diagonal line through it to show that it is not part of your answer.

5. Please read each question very carefully and answer the question clearly and to the point. Make sure that your answers are neatly written, readable and legible.

6. Leave all pages stapled together.

7. The examination period will last for 1 hours 10 minutes.

8. Stop writing immediately when the time is up.



Question 1 (10 marks) Circle the best possible answer for each question.

(a) Which of the following is not a problem that a DBMS attempts to resolve?

A. Data redundancy.
B. Data integrity.
C. Data security.
D. Database design.

D

(b) Which of the following is not one of the three levels of abstractions of a DBMS?

A. Physical level.
B. Logical level.
C. Network level.
D. View level.

C

(c) Which of the following statements is false about the relationships in the ER model?

A. A relationship can involve more than two entities.
B. A relationship can have no attributes.
C. A relationship can involve only one entity.
D. A relationship can have no participant entities.

D

(d) Which of the following is true about the weak entity in the ER model?

A. A weak entity has a key.
B. A weak entity must involve an existence dependency.
C. An existence dependency must involve a weak entity.
D. A weak entity can be uniquely identified with its own attributes.

B

(e) Which of the following is the main characteristic of left outer join?

A. Keeping all the tuples of the left join table.
B. Keeping all the tuples of the right join table.
C. Allowing repeated attributes in the result.
D. Comparing tuples with conditions other than equality

AQuestion 2 (25 marks)

You are given a library database consisting of the relations below.

BOOK (ISBN, Author_ID, Author_Name, Title, No_Of_Copies )
STUDENT (Student_ID, Name, Address)
LOAN (Student_ID, ISBN, Due_Date)

ISBN is a unique serial number for books. Author-ID and Student-ID are HKID numbers.