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

Relational databases store data in tables with rows and columns, linked by keys. They have a fixed schema. Suitable for structured data with strong relationships.

Non-relational (NoSQL) databases use various data storage models (document, key-value, graph). They have a flexible/dynamic schema. Suitable for unstructured data, scaling, and high availability.

Key differences in the table:

Characteristic	Relational Databases	Non-relational Databases (NoSQL)
Data Model	Tables, rows, columns	Documents, key-value, graphs
Schema	Fixed, strict	Dynamic, flexible
Relationships	Defined by foreign keys	Weak or absent
Scaling	Vertical (upwards)	Horizontal (outward)
Query Language	SQL	Various APIs/query languages
Examples	PostgreSQL, MySQL	MongoDB, Redis, Cassandra