August 1999
DB212 : DATABASE MANAGEMENT SYSTEMS

QUESTION 4

Total Marks: 20 Marks

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for Question 4
A company keeps a database to record information about their employees : as well as personal details, they record information about any training courses attended and about which particular posts the employee has held within the company. A sample record from the database is given below.

 
Employee Record
Employee Name : Michael Chang             Employee Number : 1234
Employee Address : 20 Pierce Road      Date of Birth : 05/12/68
Courses Attended
Course Number Description Location Date Attended Pass Level
B12
B15
C12		 Business Acct
Info Tech
Commerce		 St Ann
St Jones
Seven Oaks		 11/10/94
12/11/93
19/11/93		 B
C
B
Post Information
Job Title Dept Code Dept Name Date Appointed Salary
Accounts Exec
Business Analyst		 A312
IT05		 Accounts
IT Services		 01/09/90
01/02/94		 1500.00
2500.00

 
(a) Normalize the employee record, showing clearly the UNF, 1NF, 2NF and 3NF. State any assumptions that you make.

 

 [12]
(b) What is the objectives of Denormalisation? Why should it be carried out with great care?

 

 [2]
(c) Describe three situations where denormalisation should be used.

 

 [6]