This document contains exam questions and answers about relational database management systems. It discusses issues with storing data in a single table, how a relational database can help address this issue through normalization, and appropriate ways to set up keys and relationships between tables for a database example involving customers and products. It also covers automating ordering processes, querying the database, and ensuring privacy of customer information.

1. Exam Preparation Day
QUESTION 5 – RELATIONAL DATABASE MANAGEMENT SYSTEMS

2. a. (i)
Identify one issue with storing the data in a single table, as shown above.

3. a. (i)
Identify one issue with storing the data in a single table, as shown above.
- Repetitive data wastes disk space. Costs money.
- Repetitive data is time consuming to type. Wastes employees’ time, costs money. Inefficient.
- Repetitive data entry / typing may result in errors. Results from queries / outputs may be
inaccurate. Unreliable.

4. a. (ii)
Explain how a relational database can resolve the issue you identified in part (a)(i).

5. a. (ii)
Explain how a relational database can resolve the issue you identified in part (a)(i).
- By normalising data into source tables, in this case into Customer (or Business) and Product (or
Drinks), the amount of initial data entry is reduced. The benefits include reduced disk space,
accuracy, ease of data entry.

6. b. (i)
Discuss the effect of having Customer ID (C_ID) and Product ID (P_ID) as composite keys in Items
Table.

7. b. (i)
Discuss the effect of having Customer ID (C_ID) and Product ID (P_ID) as composite keys in Items
Table.
- This would not be an ideal composite foreign key because any combination of Product and
Customer could only occur once. This would have the effect of, for example, Freed’s Drinks only
being able to purchase 24 Coke Cans on one occasion.

8. b. (ii)
Discuss the effect of having Customer ID (C_ID) and Date (I_Date) as composite keys in Items
Table.

9. b. (ii)
Discuss the effect of having Customer ID (C_ID) and Date (I_Date) as composite keys in Items
Table.
- This would not be an ideal composite foreign key because any combination of Product and
Date could only occur once. This would have the effect of, for example, Freed’s Drinks only being
able to purchase one product on Friday October.

10. b. (iii)
Discuss an appropriate composite keys for the Items Table.

11. b. (iii)
Discuss an appropriate composite keys for the Items Table.
- C_ID, IP_TS (item purchase Time / Date Stamp)…? CHECK THIS

12. c. (i)
Two of the entities in the database are ‘Customers’ and ‘Products’. Explain the relationship
between these two entities.

13. c. (i)
Two of the entities in the database are ‘Customers’ and ‘Products’. Explain the relationship
between these two entities.
- One customer can purchase Many item types. One item type can be purchased by Many
customers. The relationship is therefore Many to Many and can be resolved by including a
transaction table with foreign keys from each source table.

14. c. (ii)
Complete the diagram above to include the Table Relationships.

15. c. (ii)
Complete the diagram above to include the Table Relationships.

16. c. (iii)
Explain the table relationship between ‘Customers’ and ‘Products’ in the context of this table
relationship diagram from part (ii)

17. c. (iii)
Explain the table relationship between ‘Customers’ and ‘Products’ in the context of this table
relationship diagram from part (ii)
It’s still a many to many relationship, but it’s been resolved by the inclusion of the Items table,
with a sub-form / portal into this via the Invoice table to include multiple purchases at any given
time. CHECK THIS, unsure what’s being asked.

18. c. again
Design an appropriate query that will output this information.

19. c. again
Design an appropriate query that will output this information.
SELECT P_ID P_Name P_CostPrice Quantity I_Date
FROM Products Products Products Items Invoice
WHERE No query, all items sorted
SORTBY or ORDERBY Quantity, descending
STOPAT 1 (for most popular product)
3 (for top three products)
**NOTE: Assumes Quantity is a summary field that totals all for a given P_ID. If not, may need an
additional field.

20. d.
Discuss how the database for Big Drink Supplies could be expanded to automate the ordering
system and reduce user error.

21. d.
Discuss how the database for Big Drink Supplies could be expanded to automate the ordering
system and reduce user error.
Repeating weekly / monthly automated orders. Script is run to email is sent to customers seven
days prior to order being processed. Order details generated from DB based on previous (or
first) orders. If nothing is done by the processing date, order proceeds. If there’s a problem,
customer can login and alter details themselves via a web interface to the database (bypassing
data entry by an employee, eliminating errors when transcribing e.g. from phone calls or email).
Whenever data is entered, a pop up or summary of the order is shown to the user to ensure that
the entered data is correct prior to the order proceeding and funds being withdrawn.

22. e.
Explain the recommended practices that a database developer will need to implement to ensure
that customer’ personal information is not disclosed to unauthorised clerical staff.

23. e.
Explain the recommended practices that a database developer will need to implement to ensure
that customer’ personal information is not disclosed to unauthorised clerical staff.
- Login details (username and password) on computer and database start up. User groups /
permissions prevent clerical staff from accessing certain information.
- Local encryption of working copies of data.
- Viewing of clients’ data will have visible data obfuscated.
- Emails, physical paper etc. with customer details are destroyed once data is entered.
- Onsite and offsite backups are secured / encrypted.

24. Questions?