Relational Databases & SQL Fundamentals Explained

Relational Databases & SQL Fundamentals

1 min readPublished 22 Jul 2026

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A relational database organises data into tables (like spreadsheets) made of rows (records) and columns (fields). SQL (Structured Query Language) is how you create, read, update and manage that data.

Interactive explainer

The Relational Model

Tables, rows, columns and keys — the foundation of SQL.

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Tables

One kind of thing.

A relational database stores data in tables (relations). Each table holds one kind of entity — Customers, Orders, Products — like a well-defined spreadsheet.

Check your understanding

1. What makes a database 'relational'?

2. What kind of language is SQL?

Keep learning

Databases & SQL Fundamentals Keys & Relationships Microsoft DP-900

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The essentials

A DBMS (Database Management System) — MySQL, PostgreSQL, SQL Server, Oracle — stores and manages the data.
Each table holds one kind of thing (e.g. Customers, Orders); columns have data types (INT, VARCHAR, DATE).
SQL is declarative — you describe what you want, and the engine works out how to get it.
Tables relate to each other via keys — the "relational" in relational database.

This is the foundation for every query you'll write and connects to cloud databases.

Interview Intelligence

How this topic actually shows up in interviews — and how to demonstrate you understand it.

Why employers ask about this

Reading and writing SQL is one of the most requested skills across tech and analytics roles.

Technical questions

What is a relational database and why is it 'relational'?+

Data lives in tables that relate to each other via keys; SQL queries across those relationships.

Behavioural questions

Tell me about learning a new technical skill quickly.+

Show a structured approach and a practical outcome, e.g. writing your first working query.

Real-world scenarios

“You're given an unfamiliar database.”+

Expected answer: Explore the schema (tables, columns, keys) first, then write simple SELECTs before anything complex.

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Employability Intelligence

Where this knowledge takes you — the jobs, skills and certifications it feeds into.

Relevant roles

Data AnalystSoftware DeveloperDatabase Administrator

Skills you're proving

SQLRelational modelData types

Recommended certifications

Microsoft DP-900 (Data Fundamentals)Oracle / SQL certifications

Career progression

Databases & SQL → analyst/developer/DBA roles.

What employers expect

That you can design a sensible schema and write correct, efficient SQL.

Frequently asked questions

What is a relational database?

A database that stores data in related tables of rows and columns, queried with SQL.

What is SQL?

Structured Query Language — the standard declarative language for working with relational databases.

What is a DBMS?

A Database Management System (e.g. PostgreSQL, MySQL, SQL Server) that stores, manages and secures the data.

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