Types of Databases (Relational vs Non Relational)

SQL Tutorials

Before you go on to learn SQL in-depth, it‘s useful to get an idea of the major types of databases. This is a common Starting Point question for beginners who are looking to learn about the storage of data: Relational vs Non Relational Databases.

Generally there are only two types of databases: relational type database and non relational type database. They have a different way of saving data which fits certain needs better than others.

What is a Relational Database

A relational database employs tables to store the data.

Tables are made up of rows and columns, rows hold records, columns hold fields, and tables link to each other by using a key, this explains to us why relations datebase are called relational.

For example, one table stores users and another table stores orders. A common column like user_id connects both tables.

The strict format makes relational databases good for dealing with structured data.

Key Features of Relational Databases

Relational databases
Store data in tables
Use a fixed structure
Connect tables using keys
Use SQL to query data
Keep data accurate with rules

Thanks to these characteristics, they can handle complex queries and wide systems.

Examples of Relational Databases

Popular relational databases include:

MySQL
PostgreSQL
Oracle Database
SQL Server
SQLite

These databases, SQL is the language used to make query.

What is a Non Relational Database

A non relational database is a very modular way of storing data.

Stores data as documents, key value pairs, graphs or columns rather than tables. Doesn‘t need to be structured.

For example, one record may have a field that another record lacks. Non relational databases are also advantageous when the data is changing frequently.

Key Features of Non Relational Databases

Non relational databases
do not use tables
allow flexible data structure
handle large amounts of data easily
work well with unstructured data
do not depend fully on SQL

Because of this flexibility, developers use them for modern and fast growing applications.

Examples of Non Relational Databases

Popular non relational databases are:

MongoDB
Firebase
Cassandra
Redis
CouchDB

Each database stores and accesses data in its own way.

Difference Between Relational and Non Relational Databases

Feature	Relational Database	Non Relational Database
Data storage	Data stored in tables	Data stored as documents or key values
Data structure	Fixed structure	Flexible structure
Relationships	Tables linked using keys	No table links
Query language	Uses SQL	Uses its own query method
Schema changes	Hard to change later	Easy to change anytime
Scalability	Grows by adding power	Grows by adding machines
Data consistency	High data accuracy	Data updates over time
Best use	Clear and structured data	Large or changing data
Examples	MySQL, Oracle	MongoDB, Firebase

When to Use Each Type

Use relational databases when:
Data is well-structured.
Matters of relationships
Accuracy is the main thing
You work almost exclusively with SQL

Use non relational databases when:
Frequently changes in the data structure.
You deal with huge data
Speed is more significant.
data does not fit into tables

Summary

Relational databases utilize tables and SQL.
Non relational databases store data in flexible formats.
Both types solve different problems and serve different needs.