Database Management Systems
moe1990
IT344Assignment2-Questions.docx|
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Question Four |
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( Assignment 1 Deadline: Day 23 / 03 / 2019 @ 23:59 [Total Mark for this Assignment is 6 ] ) ( Database Management Systems IT 344 )
( Instructions: This Assignment must be submitted on Blackboard ( WORD format only ) via the allocated folder. Email submission will not be accepted. You are advised to make your work clear and well-presented , marks may be reduced for poor presentation . This includes filling your information on the cover page. You MUST show all your work , and text must not be converted into an image, unless specified otherwise by the question. Late submission will result in ZERO marks being awarded. The work should be your own, copying from students or other resources will result in ZERO marks. Use Times New Roman font for all your answers. ) ( Student Details: Name: ### CRN : ### ID: ### )
College of Computing and Informatics
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( 1.5 Marks ) ( Learning Outcome(s): LO3 )Question One
Explain the idea behind using SEMIJOIN in distributed query processing.
( 1.5 Marks ) ( Learning Outcome(s): LO3 )Question Two
In your own words explain what is meant by Data Fragmentation? Given the following customer relation, apply the horizontal fragmentation based on customer's gender.
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Customer_id |
Name |
Area |
Payment type |
Sex |
|
112 |
Ahmed |
jeddah |
Credit card |
male |
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211 |
Khaled |
riyadh |
cash |
male |
|
311 |
Noura |
madinah |
cash |
female |
( 1.5 Marks ) ( Learning Outcome(s): LO3 )Question three
Suppose DBA has created three accounts Alpha, Bravo, and Charlie. Alpha is the owner of the following database schema;
STUDENT: Sid, Lname, Fname, Phone, Gpa
COURSE: Cid, Title, Level, Units, Location, Time
INSTRUCTOR: Iid, Lname, Fname, Designation, Salary, Dept
.
Write SQL statements to grant or revoke following privileges. "
Create the views if and when necessary.
a) Alpha wants to allow Bravo to retrieve information from STUDENT and INSTRUCTOR tables and also to be able to propagate the SELECT privilege to other accounts.
b) Alpha wants to give a capability to retrieve Title, Location, and Time from the COURSE relation where the Level = 6 to Charlie and to be able to propagate the privilege.
c) Alpha decides to revoke the SELECT privilege on the STUDENT relation from Bravo
( 1.5 Marks ) ( Learning Outcome(s): LO3 )Question Four
Suppose a public sector university in Saudi Arabia wants to implement the strictest access control to its databases. Instead of allowing each user to control access to their own data, the university wants system resources to be controlled by the operating system under system administrator with an hierarchical approach of assigning security labels to the resource objects.
Answer the following questions;
a) Which database security mechanism would you recommend to the university?
b) Motivate your recommendation by describing two advantages.
c) What are the two disadvantages of using this approach?
