Beginner~6 weeks6 steps

SQL & Databases

Learn the language of data: querying, joins, modeling, indexes, and transactions with PostgreSQL — a skill every developer and analyst needs.

1
Relational database concepts
Tables, rows, primary and foreign keys — how relational databases organize data.
- DocsConcepts (PostgreSQL Tutorial)
- ExerciseSQLBolt — Introduction to SQL
2
Querying with SELECT
Filter, sort, and shape result sets with WHERE, ORDER BY, and LIMIT.
- ExerciseSQLZoo — Interactive Tutorials
- CourseMode SQL Tutorial — Basics
3
Joins & aggregation
Combine tables and summarize data with GROUP BY and aggregate functions.
- DocsJoins Between Tables (PostgreSQL Tutorial)
- ExercisePostgreSQL Exercises
4
Data modeling & normalization
Design schemas that avoid duplication and stay consistent as they grow.
- ArticleDatabase Normalization — 1NF, 2NF, 3NF Explained (freeCodeCamp)
- DocsData Definition (PostgreSQL docs)
5
Indexes & query performance
Understand how indexes work and how to make slow queries fast.
- ArticleUse The Index, Luke — SQL Indexing Explained
6
Transactions & practice
Keep data correct under concurrency, then drill everything with real exercises.
- DocsTransactions (PostgreSQL Tutorial)
- ExercisePostgreSQL Exercises — full drill

Relational database concepts