(a) The adoption of database systems as a way of managing information systems is gaining popularity over standard file
(i) State the features of a database management system that provide data security and integrity.
(ii) What problems are caused data redundancies?
(iii) Centralized control avoids unnecessary data redundancy or duplication.
What precautions should be taken into account -in the process of establishing a centralized data control system to avoid data redundancy?
(b) It is important to bear in mind that information may be relevant to people outside the organisation as well as to its” internal management and employees. Sometimes it
happens that some decisions relating to an organisation are taken outsiders.
State six examples of decisions relating to an organisation that may be taken outsiders
a) Database system
This refers to a system composed of a group of related files.
This is a group of records of the same type.
This refers to a group of related fields e.g. a student record may be composed of fields such as student name, student number, course, date of birth, etc
Database management system
This refers to a complex software system that constructs, expands and maintains the database. It also provides the controlled interface between the user and data in the database.
(i) Features of a DBMS that provide data security and integrity:
1. Usernames and passwords- used to prevent unauthorized
2. Transaction locks i.e. write locks and read locks. Write locks prevent other processes(programs) from updating data currently being updated a process. Read locks prevent any other processes from updating data that is currently being read a process.
3. Checkpoints and journals. A checkpoint is a ―snapshot‖ of the database before it was updated processes/programs and the journal holds details of updates subsequently made. In the event of failure, the recovery process can rebuild the database from checkpoints and journals.
4. User rights and privileges- access to files or fields of records could be granted depending on the user privileges.
5. Encryption- coding of data special algorithm that renders them unreadable without decryption.
Integrity checks e.g. checks on relationships amongst tables to ensure that they are valid and data validations
(ii) Data redundancy
This refers to the presence of duplicate data in multiple data files. Data redundancy occurs when different divisions, functional areas, and groups in an organization independently collect the same piece of information. For instance, within the commercial loans division of a bank, the marketing and credit information functions might collect the same customer information contained in separate files.
Problems caused data redundancies:
1. Large storage space requirements
Since each functional area of an organization maintains the same piece of information, the resource requirements (hard disk, optical disk, magnetic tape) may be very large.
2. Problem of securing all the redundant data
Though the data in such a database is redundant, it must still be secured from unauthorized access. This task is very difficult to implement because each functional area of an organization holds the data.
Since data is collected and maintained in so many different places, the same data may have different meanings in different parts of an organization. Simple data items such as the fiscal year, employee identification, and product code can take on different meanings as programmers and analysts work in isolation on different applications.
4. Difficulty in performing updates
To update a redundant data item, one must update all instances of the redundant item in all the department files of an organization. This is clearly hectic!
5. Compromised system integrity
In cases where only one instance of a redundant data item is updated, the system integrity is compromised since the other instances of the redundant data item in the rest of the organization‘s departments will differ from the updated instance of the redundant data item.
(iii) Precautions that should be taken into account in establishing a centralized data control system to avoid redundancy:
1. One should ensure that adequate security mechanisms are in place to ensure that users are granted access to only what they are supposed to access.
2. One should ensure that the system is fault tolerant i.e. it should be not too centralized as to be vulnerable to failure.
b) Decisions relating to an organization that may be taken outsiders:
1. Changes in value added tax
2. Changes in materials costs
3. Change in bank account charges
4. Regulation of prices e.g. petroleum prices, matatu fares, etc
5. Regulation of bank interest rates
6. Changes in legislation e.g. changes to clauses in the Companies Act
7. Imposition of exports quotas