Hierarchical Database Model | History, Examples and Comparison

Published: 30 Dec 2024

What is a Hierarchical Database Model?

Data is stored in a set of records connected by a parent-child connection in a hierarchical database, which arranges data in a tree-like structure. The structure is comparable to a family tree or organizational chart, where each parent record may have several child records, but each child record only has one parent.

Table of Content

What is a Hierarchical Database Model?
History of Hierarchical Database Model
Hierarchical Model of Database
Examples of Hierarchical Database Model
Hierarchical Model in DBMS
Application of Hierarchical Model
Advantages of Hierarchical Database Model
Disadvantages of Hierarchical Database Model
Difference Between Hierarchical and Relational Database
Conclusion About Hierarchical Database
FAQS

History of Hierarchical Database Model

One of the earliest approaches to organizing and storing data in computer systems was the hierarchical database model, which was created in the 1960s. It was mainly used by companies to manage large amounts of structured data. IBM introduced a popular hierarchical database called IMS (Information Management System) in 1966 to help NASA manage the complex data for the Apollo moon missions.

Back then, the hierarchical model was a big advancement because it provided a clear way to organize data, especially for applications that needed to handle a lot of information with simple, one-to-many relationships. However, as technology advanced, more flexible models like the relational database model became popular in the 1970s, as they could handle more complex data connections.

Hierarchical Model of Database

Data can be arranged in a tree-like structure using a hierarchical database model, in which each item of data is connected in a “parent-child” connection. In this model:

Each parent can have multiple children, but each child has only one parent.
It’s like an organizational chart or a family tree, with one main root (the top level) and each level below branching out.

Examples of Hierarchical Database Model

Imagine a library database:

The top level (or root) is Library.
Under it, there are categories like Subjects (Science, History, Literature).
Under “Science,” there are subcategories like Biology, Physics, and Chemistry.
Each of these subcategories can have books (the final “child” level).

Hierarchical Model in DBMS

In DBMS (Database Management Systems), the hierarchical model is a way of organizing and storing data in a tree-like structure, similar to a family tree or an organization chart.

Tree Structure: A tree structure is a way of organizing data in a shape that looks like an upside-down tree. It begins with a single root, or top point, from which several connected points, or nodes, branch out. Each node has child nodes beneath it, forming a parent-child relationship. This structure is helpful when displaying data that naturally falls into levels, such as in organizational charts or family trees.

One Parent, Many Children: In a “one parent, many children” structure, each parent item can have multiple children linked to it, but each child has only one direct parent. For example, in a school, one class (parent) can have many students (children), but each student belongs to only one class. This setup is common in systems that use a hierarchical structure, like family trees or organizational charts.

hierarchical database, hierarchical database model example

Application of Hierarchical Model

File Systems: Many computer systems use a hierarchical model to organize files. The main folder (or root) contains subfolders, which can have their own subfolders and files, making it easy to navigate through levels.

Organizational Charts: Companies use hierarchical models to show employee roles. The CEO is at the top, with managers below, and each manager supervises a group of employees. This structure clearly defines reporting lines.

Library Catalogs: Libraries organize books in a hierarchy. The top level might be Genres (like Fiction, Non-Fiction), which branch into Sub-genres (Mystery, Biography), and finally to individual books. This makes searching for specific types of books easier.

Advantages of Hierarchical Database Model

Simple Structure: The parent-child hierarchy is easy to understand and use, especially for data with a natural order, like organization charts or file systems.

Fast Data Access: Since the structure is predefined, finding data that follows the hierarchy (like finding files in folders) is fast and efficient.

Data Integrity: With clear relationships, it’s easy to maintain data consistency, as each child has a single, defined parent.

Disadvantages of Hierarchical Database Model

Limited Flexibility: The model is rigid, so it’s hard to make changes or add connections between different parts of the hierarchy.

Duplication of Data: Some data may need to be repeated across different branches, which takes up space and can lead to errors.

Complex Relationships: It’s not ideal for complex data relationships where a record needs multiple parents, as it only supports one parent per child.

Difference Between Hierarchical and Relational Database

Relational	Hierarchical Database
Data is stored in tables	Data is stored in a tree format
Supports many-to-many	Supports one-to-many only
More flexible and scalable	Less flexible and rigid
Uses SQL queries	Uses path-based navigation
Customer data, finance, inventory	File system, org charts, XML
Easier to manage and update	Harder to manage with complex data

Conclusion About Hierarchical Database

A hierarchical database is a useful way to store data in a tree-like structure with clear parent-child relationships. It works best for data that naturally fits into levels, like organization charts or file systems, making it simple to navigate and manage structured data. However, it’s less flexible for complex data relationships and is not as commonly used today as more adaptable models, like relational databases. Despite these limitations, the hierarchical database model laid an important foundation for modern data organization methods.

FAQS

What is a hierarchical database model?

Each record has one parent and numerous children in this tree-like data organization method. This model stores data in a top-down approach, similar to a family tree.

What is an example of a hierarchical model?

An example is an organizational chart showing a company’s structure from the CEO down to employees. Another example is the file system on your computer.

What is an example of a hierarchical pattern?

A family tree is a good example, showing generations from grandparents to children. Another example is the classification of animals from the kingdom to species.

What is a simple example of hierarchy?

A school structure where the principal is at the top, then teachers, then students, is a simple hierarchy. It shows different levels of authority.

What are the four database models?

The four common models are hierarchical, network, relational, and object-oriented. Each organizes data differently based on use.

Is Excel a database?

Excel is mainly a spreadsheet tool, not a full database. It can store data but lacks advanced database features.

What distinguishes relational, network, and hierarchical models from one another?

Relational employs tables with flexible links, a network for multiple parent-child relationships, and hierarchical arranges data in a tree with one parent per child. Relational is more flexible than the others.

Why use a hierarchical model?

It is simple and fast for data with a clear parent-child relationship. It works well when data is naturally organized in a hierarchy, like file systems.