Introduction to Data Models

In order to store data in a database system, we need some data-structures. Hence the database systems we use normally include some complex data structures which we normally do not use. To make the system efficient in terms of data retrieval, and reduce complexity in terms of usability, developers use data abstraction i.e., hide irrelevant details from the users.

In order to achieve this abstraction, we use data models.

A data model is a collection of concepts or notations for describing data, data relationships, data semantics, and data constraints.

We will highlight what these terms mean in the next few lessons.

Most data models also include a set of basic operations for manipulating data in the database.

Types of data models #

The different types of data models can be classified into the following categories:

1. High-level conceptual data models #

High-level conceptual data models provide a way to present data that is similar to how people perceive data. A typical example is an entity-relationship model, which uses concepts like entities, attributes, and relationships.

Entity relationship model #

An entity represents a real-world object such as an employee or a project. The entity has attributes that represent properties such as an employee’s name, address, and birthdate. A relationship represents an association among entities; for example, an employee works on many projects. A relationship exists between the employee and each project.

2. Record-based logical data models #

Record-based logical data models provide concepts users can understand but are still similar to the way data is stored on the computer. Three well-known data models of this type are: hierarchical, network, and relational data models.

Hierarchical model #

In a hierarchical model, data is organized into a tree-like structure, implying a single parent for each record. This structure mandates that each child record has only one parent, whereas each parent record can have one or more child records. This concept is illustrated below: