SQL tutorial

Learn SQL step by step

A practical SQL tutorial covering the fundamentals of reading and writing queries, along with common patterns used in analytics, backend work, and reporting.

Core SQL concepts

SELECT

The first step in any SQL workflow: choose the columns you actually need.

WHERE

Filter rows by conditions that match the business question.

ORDER BY

Sort results so reports and outputs are easier to interpret.

GROUP BY

Aggregate and summarize rows around meaningful categories.

JOIN

Connect related data across tables in a relational database.

Subqueries

Add nested logic for filtering or derived result sets.

CTEs

Break a complex query into readable logical steps.

Window functions

Calculate trends and rankings without collapsing rows.

Transactions

Keep changes consistent when multiple operations belong together.

Indexes

Speed up table lookups and improve query performance.

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