Data Models

A data model defines how data is structured, stored, related, and manipulated in a DBMS.

1 · Relational Data Model

2 · Entity-Relationship (ER) Model

A conceptual model representing data as entities, attributes, and relationships — e.g. Student — enrolls — Course. Purpose: design the database structure before implementation.

3 · Hierarchical Model

Data is organised in a tree with parent–child links; each child has only one parent. Examples: University → Department → Student, a file system.

4 · Network Model

An extension of the hierarchical model where a child can have multiple parents, forming a graph. Example: a student enrolls in many courses, and a course has many students.

5 · Object-Oriented Model

Data is stored as objects (like OOP), combining data (attributes) and behaviour (methods). E.g. a Person superclass with Student, Doctor, Engineer subclasses (inheritance).

6 · Semi-Structured Model

Data has no fixed schema; structure is flexible. Two common formats:

<employee id="34594">
  <firstName>Heather</firstName>
  <lastName>Banks</lastName>
  <salary>72000</salary>
</employee>

{
  "emp_name": "Shubham",
  "email": "shubh@gmail.com",
  "job_profile": "intern"
}

Quick comparison