What is the difference between relational and non-relational databases?

Relational databases (RDB) are based on tables with clearly defined schemas and relationships between them. They use SQL for queries and ensure data integrity through transactions and constraints.

Non-relational databases (NoSQL) are more flexible, do not require a fixed schema, and can store data in the form of documents, key-value pairs, graphs, or columns. They are better suited for large volumes of data and distributed systems but may sacrifice strict integrity for performance and scalability.

Example:

• Relational DB: MySQL, PostgreSQL
• Non-relational DB: MongoDB, Redis

In embedded and IoT systems, the choice depends on data structure requirements, device resources, and the need for scaling.