DATABASE MANAGEMENT SYSTEMS

DATABASE MANAGEMENT SYSTEMS

ANSWER QUESTION ONE AND ANY OTHER TWO QUESTIONS

QUESTION ONE (COMPULSORY) (30MKS)

 

  1. a) Describe the phrase ‘three-tier architecture’ with respect to the following two

distinct systems:

  1. i) Databases and the ANSI-SPARC model                                       (3 marks)
  2. ii) Databases and the Web                                                                  (3 marks)
  3. b) Explain, using your own examples, how the following database concepts are implemented and how they relate to each other:
  4. i) Data integrity                                                                                 (2 marks) ii)        Data validation                                                                               (2 marks) iii)       Data security                                                                                  (2 marks)
  5. c) Illustrate four benefits of “Views” in database.                                         (8 marks)
  6. d) Outline and explain five advantages of using a database system over the use of spreadshee  (5 marks)
  7. e) For each of the following relational concepts, explain the key ideas behind them and provide suitable examples:                                                                  (5 marks) i)    Entity Integrity
  8. ii) Referential Integrity

QUESTION TWO (20MKS)

  1. a) The table below stores details of students and the overall grade each student obtained in different m The table has a composite primary key
  2. i) Which Normal Form does the above table violate and why         (4 marks)
  3. ii) Normalise the table up to the normal form identified in question i)

(5 marks)

 

 

  1. b) Describe five characteristics of the database approach and contrast with the file- based approach  (5 marks)
  2. c) The traditional database approach is centered on the relational model of data and has been existing yea Explain six reasons why the relational model has endured despite the rise of Object Oriented techniques over the last 30 years  (6 marks)

 

 

QUESTION THREE (20MKS)

 

  1. a) Describe two mechanisms for achieving data integrity                             (4 marks)
  2. b) JISP Electronics Discourse JISP is a company that sells a range of electronic products to its customers over the interne Customers purchase products using an on-line order entry system called a ‘shopping cart’. A collective has been set up involving a group of suppliers who supply JISP with the products they need to meet customer orders. This means JISP can negotiate discounted prices for specific products purchased from the supplier group. Each product has an initial price (discounted price) that decreases as the total quantity of products that JISP sell to customer’s increases. JISP also benefits from having a higher priority for the supply of products from the supplier group in the collective than other internet shopping companies. JISP make a profit on each product it sells as the discounted price includes a small commission that JISP receive on sales of that product. The time that a product can be bought by customers at the discounted price is called

the offer period. JISP raises supplier orders (Figure A3) for products that customers have ordered from them and holds the products in a warehouse before dispatching them to customers. Suppliers can supply JISP with products on demand or ‘just in time’.

 

Exract an ER data model for JISP                                                            (10 marks)

 

  1. c) Explain three reasons why security of data in a database is becoming an

increasing concern.                                                                                     (6 marks)

 

QUESTION FOUR (20MKS)

 

  1. a) Highlight two techniques and two precautions that can be used in each of the following:
  2. i) Allowing users to connect to the database                                     (4 marks)
  3. ii) Authorizing users to perform certain actions within the database (4 marks)
  4. b) Define the term ‘Relation’ in the context of the Relational model of data

 

(2 marks)

i) Give five examples of the type of data held in this catalogue (5 marks)
ii) Outline five purposes of the catalogue (5 marks)

 
  1. c) Most DBMS products use a data dictionary (also called the system catalogue) to hold meta-da
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