The relationship between Customer No and Friend No was set up using a Query by Example (QBE) Graphics User Interface. To set up this relation, the QBE software required that a duplicate of the customer record was shown on the screen. This is shown as Customer Record_1 in the diagram below. You have been asked to make all the necessary changes to the company's database in order to accommodate the changes.

 

a) Does the existence of this relationship require that both Customer Record and its duplicate Customer Record_1 are permanently stored? Give a reason for your answer. 

b) State TWO advantages and TWO disadvantages of using a QBE interface rather than a Data Manipulation Language (DML) such as mySQL to set up queries or relationships.

c) The programming department usually gives attributes the same label (name) as the attribute to which they are related in another relation. Explain why it is impossible to change the label of Friend No to Customer No. d) Explain clearly the terms:- Relation, Tuple, Foreign Key, Primary key.

Customer Record Customer No Name Address Friend No