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Heinemann Questions


Chapter 2: Information Systems and Databases

2.3 Storage and Retrieval

1. Explain the difference between a database and a DBMS.
 A DBMS is a software package that allows users to access a database so they can enter, maintain and view that data. A database contains the data, and the DBMS provides access to this data.
2. Describe accessing data using an index.
Data is accessed by referring to the index and obtaining the exact location of the data. 
3. What is a distributed databse?
A database located at more than one site. 
4. Briefly describe some of the storage media used by information systems.
  • Hard disk - A disk made of metal or glass covered with magnetic material. They are mounted inside the computer's case usually (fixed) and storage capacity measured in Gb. They use direct access.
  • Optical disk - A polycarbonate plastic disk with a reflective layer of metal covering the surface. Data is read and written using laser technology. Uses direct access and includes CD-ROMs ad DVDs.
  • Removable cartidge - A hard disk encased in a metal or plastic cartridge and can be removed like a floppy disk. They are fast (but not as fast as hard disks) and use direct access.
  • Magnetic tape - A very long, thin strip of plastic, coated with a thin layer of mangnetic material. The tape is wound on two reels inside a cartidge. Can store large quantities of data inexpensively and are usually used for backups. Use sequential access. 
5. What is public key encryption?
Involves a public key that is widely availbale and a private key that is kept secret. The public key is used to encrypt the message and the private key to decrypt. 
6. Describe the process of backup and recovery.
When performing backup, another copy of the data is made so that it can be used to rebuild the system if something occurs. If the system goes down, the data is retrieved and the systems is rebuilt or recovered. 
7. Explain the difference between searching and sorting.
Searching is the process of examining the databse to retrieve data. Sorting is the process of arranging data in a particular order. 
8. What is QBE?
 Query by example, which is a common method for constructing a query.
9. List four keywords in SQL and descibe their purpose.
  • SELECT - The data to be displayed.
  • FROM - The source of the data.
  • WHERE - The query.
  • ORDER BY - The order in which the results are to be displayed. 
10. How is a search engine index built?
By regularly scanning the Web for new sites and accept submissions from Web page authors.
11. Describe a search engine that offers directories.
A search engine that offers directories would have lists of Web sites organised into categories. 
12. What is a search robot?
A program that accesses Web sites and gathers information for search engine indexes. 
13. Write the meaning of the following queries:
(a) Class = 12*
Any year 12 class followed by multiple characters of any kind. 
(b) Postcode = 261? 
 A four digit post code beginning with 261.
(c) LastName begins with H
From the field LastName, all the last names beginning with H.
(d) Assessment > 60
 All assessments greater than 60.
(e) FirstName = "Peter" AND Suburb = "Mossman"
 First name is Peter and suburb is Mossman.
(f) Colour = "Red" AND Cost > $500
 Colour is red and costs more than $500.
(g) LastName = "Tran" OR PostCode = "2534"
 Last name is Tran or post code is 2534.
 (h) StreetNumber = "9" OR Price < $500
 Street number is 9 or price is under $500.
14. Write out queries using relational operators for each of these searches:
(a) Year 12 boys in the school.
(b) Borrowers who live either in Auburn or Lidcombe.
(c) Girls in the netball club who are eligible to play in 18 and under teams.
(d) All customers who owe more that $10 000 for the month of Juy.
15. The following questions refer to the School database in Figure 2.18.
(a) Write down the StudentId of the second record if sorted on 'First Name' in ascending order.
(b) Write down the StudentID of the third record if sorted on 'Phone Number' in descending order.
(c) Which of the 'Mullins' would come first if the primary sort field was 'LastName' and a secondary sort field was 'StudentID'.
(d) Write down the StudentID of the first record if the primary sort field was "Address' and a secondary sort field was StudentID.

2.5 Issues Related to Information Systems and Databases

Learning Activities
1. A flat-file database is used by a school for student records. There are separate files for student data, financial data, teacher data and assessment results. A relational database has been suggested to the principal as a better system. Outline the advantages of a relational database over a flat-file database in this particular context. Your answer should contain references to data accuracy, data redundancy, security and development time.
In this context many relationships exist and need to be managed and a relational database would be very suitable for this as it can help make updating data efficient. However, the amount of links that may result can reduce security.
2. Privacy and access to data are two important issues related to databases. Consider a student database containing name, address, gender, ethnicity, family, financial status, health, discipline record and assessment results. Should access to this data be given to the student, other students, teachers, the Department of Education, potential employers or other organisations? Is there a need to provide some gorups with limited access? Explain your answers.
Some of the data does not concern some groups such as other students. In some ways, allowing teachers access seems acceptable as they should be given access to the student's academic progress however finanacial status is irrelevant. The Department of Education is similar to teachers but also have less personal contact with students so should not be disclosed the student's ethnicity. As for employers, depending on the situation, they should not be given access to the student's past dscipline records if this limits their employment opportunities as this does not necessarily reflect the ptential employee's reliability.

3. "Databases should not have the same copyright protection as books and software." Do you agree with this statement? Give reasons.
No, as books and sofware have copyright protection to protect their creative works and allow them to earn money from it. A database contains information about other entities, especially individuals and technically not created by the developer.

4. Max Music is a small business that offers an online shopping service for customers via the Internet. Customers place orders for CDs using their credit cards and register preferences for categories of music. This data is stored in a database. Research indicates that preferences for music are also a good indicator for book and video preferences. Describe the ethical issues raised if Max Music sells each customer's preferences to a book company.
If customers had initially signed a contract which agreed to this then Max Music is legally allowed to. However, the customers should have been made aware of how the data will be used and have a rigbht to inspect and correct this data. If the purpose has not been stated at the time it was collected, they must obtain consent from the customers. Only authorised people with a genuine need should be able to access and use this data. Max Music must also be responsible for only the data requested is given as relationships may reveal other personal details.