(a)(i) What is data model? (ii)State three types of data model (b)(i) List three approaches to data modeling. (ii) Explain any one approach listed in1(b)(i)

Answer Details

This question tests knowledge of data models and approaches to data modelling.

(a)(i) Data model. A data model is a way of describing and organising how data is structured, stored and related in a database, defining the data elements, their attributes and the relationships between them.

(a)(ii) Three types of data model.

• Hierarchical model: data is organised in a tree-like, parent-to-child structure.
• Network model: data records are linked, allowing a child to have several parents (many-to-many links).
• Relational model: data is stored in tables (relations) of rows and columns, linked by common fields.

(The object-oriented model is another acceptable type.)

(b)(i) Three approaches to data modelling.

• Conceptual data modelling (high-level, entity/relationship view).
• Logical data modelling (detailed structure independent of any DBMS).
• Physical data modelling (how the data is actually stored in a particular DBMS).

(b)(ii) Explanation of one approach. Conceptual data modelling gives a high-level, technology-independent picture of the data. It identifies the main entities (such as Student, Course), their key attributes, and the relationships between them, usually drawn as an entity-relationship diagram. It focuses on what data the organisation needs and how items relate, not on how the data will physically be stored, so it is used early in design to agree the requirements with users.

Examination reminder: do not confuse the types of data model (hierarchical, network, relational) with the levels/approaches of modelling (conceptual, logical, physical); this question asks for both.