With the aid of a diagram, describe the Hierarchical Database Model.

Source: KCSE Computer Studies 2012 - Paper 1
Question Number: 20 (a)(b)(c)
Marks: 15 Marks

​(a) With the aid of a diagram, describe the Hierarchical Database Model. (4 marks)

From Topic: Databases
From Subtopic: Types of database models
Question Level: Form 2

​Requirements

​Candidates were required to understand and apply Database Design.

​Weaknesses

Many candidates did not attempt this question and those who attempted performed poorly.

Expected responses

1. Data items are arranged in a tree like format.
2. Access is through a single path and all from one single item called the root component.

(b) List three factors that should be considered when developing a database application and give reasons why each should be considered. (6 marks)

From Topic: Databases
From Subtopic: Creating a Database
Question Level: Form 2
Expected Responses

Factors

1. Complexity of data/user needs/user friendliness
2. Security and integrity
3. Complexity of DBMS
4. Volume of data/size
5. Software compatibility with existing DBMS
6. Cost of the data base

(any 3 x 1 = 3 marks)

Reasons​

1. Complexity of data - Complex data requires complex DBMS.
2. Security and integrity - Data which is intended to be secured in terms of access, can be handled by complex DBMS which provides for such requirements.
3. Complexity of DBMS - Complex DBMS do require complex skills, hence more training. It is therefore costly to run/use such system.
4. Volume of data - Voluminous data require to be ran on stable application. They also take up extra computer system resources.
5. Software compatibility - enables pre-existing databases to be exported to the new one.

(corresponding explanation x 3 = 3 marks)

​(c) (i) Name three types of validation checks during data entry. (3 marks)

From Topic: Databases
From Subtopic: Creating a Database
Question Level: Form 2
Expected Responses

1. Field type/data type
2. Field size
3. Format
4. Reasonableness
5. Range constraint
6. Presence check

(any 3 x 1 =3 marks)

​(ii) Differentiate between primary key and index key. (2 marks)

From Topic: Databases
From Subtopic: Creating a Database
Question Level: Form 2
Expected Responses

• Any index key is a database feature used to speed up search and sort operations in a table;

whereas

• a primary key is a field that enforces uniqueness in a table so that one record is not entered twice

or

• a primary key is a field that uniquely identifies each record.

(1 mark x 2 = 2marks)

​Advice to the teachers

Teachers to guide the students in acquiring the important concepts in database design

more kcse/mocks q & a

---