Page 211 - IT_V1.0_Class10
P. 211
The following figure shows the hierarchical data model:
CEO
Marketing Sales
Digital Brand Market International Retail Corporate
Research
East Coast
In the figure, “CEO” is the main category, like the trunk of a tree. It has two main branches: “Marketing”
and “Sales”. Each of these branches then further divides into more specific types, like “Digital”, “Brand”, and
“Market Research” under “Marketing”. This setup shows how one category can have several subcategories,
like a family tree.
Network Data Model
The Network Data Model allows multiple records to be linked to a central master file. While offering greater
flexibility in data organisation, this model can present challenges in management compared to simpler
models.
The following figure shows the network data model:
University
Computer
Maths Department
Department
Library Seminar Computer Lab
In the figure, “University” stands as the starting point, with two branches: “Maths Department” and “Computer
Department”. “Maths Department” has three sub-branches, while “Computer Department” has two. As
mentioned earlier, this model allows multiple parents, so “Seminar” and “Computer Lab” have two parents
each: “Maths Department” and “Computer Department”.
Relational Data Model
The relational data model is built on the concept of establishing relationships between two or more tables
within the same database. It is the most widely used database model, introduced by Edgar F. Codd in 1970. In
this model, data is organised into tables, each consisting of rows and columns. Each row represents a record
or entity, while each column represents a specific attribute or field of that entity.
The relational model is characterised by its ability to relate data across different tables using common fields,
hence the name “relational database model.” These relationships help maintain data integrity and enforce
constraints such as referential integrity.
Introduction to Database Management System 209

