Learn SQL - Database & Queries

Learn SQL by writing queries against a real database on your phone. Short lessons explain each idea, then you type the statement, run it and see the rows come back. It is an SQL tutorial, a database course and an SQL practice lab in one app, with an AI mentor for the join that will not behave. WHAT'S INSIDE • 46 courses with 183 lessons, from SQL for beginners (A1) to advanced database topics (C2) • A database on your device: SQLite runs your code on the phone, and lessons that need PostgreSQL syntax run in PostgreSQL on the phone too. No server round trip, and your tables stay between sessions • SQL editor and sandbox: write anything, browse the schema, reopen earlier statements from the history and see the plan with EXPLAIN • Practice tables ready to use: users, orders, order items, products, categories, employees, departments, sales and events • Daily Query: one SQL query to write each day, checked against the data on your phone • 20 guided database projects, checked by the result you get, not by the text you typed • 30 missions (easy, medium, hard) • World Coding Challenge: 3 global rounds every day • Quizzes, flashcard review, a cheat sheet, interview questions, streaks and a skill tree • Final exam and certificate (Pro) THE ARENA: PRACTICE GAMES • Data Detective: 6 cases, where each correct answer unlocks the next clue • Dataset packs: films, football matches, albums and weather, with guided questions • Your own data: import a CSV or JSON file and explore it (CSV export with Pro) • Duel: three tasks against a target pace • Golf: return the same rows with a cheaper plan • Fix It: a statement that runs but returns the wrong rows, with a row-by-row diff • Drills: spaced review built from your own mistakes • Schema Designer: design tables, get lint hints and run the generated DDL • Interview Simulator: 5 timed questions and a follow-up, then a report • Rush: a 60-second game with a combo score WHAT YOU'LL LEARN • SELECT, WHERE, ORDER BY, LIMIT and filtering patterns • Aggregate functions, GROUP BY and HAVING • JOINs: inner, left, self joins and advanced patterns • INSERT, UPDATE, DELETE, NULL handling, CASE, dates, strings and numbers • Constraints, keys and database design • Subqueries, CTEs, recursive queries and window functions • Views, JSON and JSONB, arrays, GROUPING SETS, ROLLUP and CUBE • Performance: EXPLAIN, indexes, transactions and concurrency • Triggers, stored procedures, row-level security, backup and restore • Partitioning, replication, data warehousing and sharding Most lessons teach standard SQL. The advanced courses use PostgreSQL features. HOW A SESSION LOOKS 1. Answer today's question or continue your lesson 2. Read a short explanation and try the example, many with a Run button 3. Open the editor, change the code, run it and read the result table 4. Ask the AI mentor why a join returns too many rows WHO IT'S FOR • Beginners starting from zero • Analysts and marketers who want to pull their own data • Developers adding databases and PostgreSQL to their skills • Students and career-switchers heading into data roles • Anyone doing SQL interview prep FREE AND PRO Free: the first course (Introduction to SQL & Databases), a preview of every other lesson, the editor and sandbox, the Daily Query, 1 guided project, 2 missions, part of every Arena mode (for example 3 duels and 3 drills a day, 1 case and 1 dataset pack) and a daily AI mentor allowance. The free version shows ads. Pro: every course and lesson, all projects and missions, the full Arena, the final exam and certificate, AI tools, AI mentor without the daily limit, and no ads. Pro is a weekly, monthly or yearly subscription, or a one-time lifetime purchase. The app is available in 22 languages. Learn SQL is an independent app, not affiliated with the PostgreSQL Global Development Group or the SQLite project.

• Refreshed look and smoother experience across the app • Improved translations — lessons and screens in your language Thanks for learning with us — your reviews help us improve!