What to look for in a SQL app for your phone
A phone is a good place for short, regular SQL practice and a poor place for long sessions. Before you compare apps, decide what you want the app to do, then check four things in its App Store listing.
- Do you write real queries? Some apps run the SQL you type against sample tables. Others ask multiple choice or fill in the blank questions. Both help you remember syntax, but only writing whole queries gets you ready to write them at work or in an interview.
- How do you enter SQL? Typing
GROUP BYon a phone keyboard gets old fast. Look for an SQL keyboard, tap to build input or templates you can edit. - Does it work offline? If you practice on a train or a plane, check whether the listing says the lessons and queries run on the device.
- What's free? Every app here is free to download, with in-app purchases. The listings differ a lot in what the free part covers, so read that section before you start.
The table above sorts the apps by the job each one does well. Here are the same apps grouped by what you're trying to do.
If you want SQL and nothing else
SQL Practice: Learn Database is built around 15 minute daily sessions. You write and run real queries, with easy, medium and hard exercises, quick drills and a daily challenge. Its listing says the core lessons, exercises, drills and streaks are free, while progressive hints, detailed comparisons with the expected output and the SQL Patterns lessons need Pro. It's iPhone only.
SQL Code Play feels more like a small database you carry around. You get a query workspace with Code and Output tabs, a sample database of employee, meeting and room records, and lessons that go from SELECT and joins to CTEs, window functions, date calculations and JSON. The workspace and lessons run on the device. Its challenges are multiple choice and fill in the blanks rather than full queries, and the app shows ads unless you subscribe.
SQLite: SQL Practice takes the opposite view of quizzes: you type every query yourself in a SQLite editor. You can also create your own tables, which helps when you want to rebuild a problem from work. Its listing names topics from simple SELECT up to joins, subqueries and aggregate functions.
If SQL is one subject among several
DataCamp suits a data analyst or data science path. Its app has courses in SQL, Python, R and AI, and its SQL description mentions analysis in PostgreSQL. The opening chapter of each course is free; the rest is a subscription.
Sololearn teaches more than 20 languages in short lessons, with SQL among them, and has an AI helper you can ask when a lesson stops making sense. Mimo is aimed at people who want a software developer career, so SQL sits next to Python, JavaScript and web development. Both are good if you're learning to code in general and want SQL as part of that. If SQL is the only thing you need, a SQL-only app spends every lesson on it.
If you're preparing for an interview
QueryQuest is gamified, with XP, streaks and hearts, and moves through 8 levels from basic SELECT to CTEs, window functions and a final level of common interview questions. All 8 chapters and unlimited hints come with a one-time Pro purchase rather than a subscription, and its lessons work offline.
Query Dojo is our app, so weigh this paragraph with that in mind. It's built around interview-style questions on four sample databases, with timed mock interviews of 25 minutes and 4 questions without hints, and a readiness score at the end. When a query is wrong, it tells you what's off, such as missing columns or the wrong row count. You can type or build queries by tapping tiles. The app is for iPhone and iPad and needs a subscription. If you want to try the questions first, many of the practice questions on this site are free in the browser with no signup. It runs SQLite only.
A simple plan for practicing on your phone
Pick one app and stay with it for a month. Switching apps every week feels productive but mostly resets you to the easy lessons.
- Week 1: the basics. SELECT, WHERE, ORDER BY and LIMIT. Do a few minutes a day, every day, rather than one long session.
- Week 2: joins and grouping. Get comfortable with INNER and LEFT joins, then GROUP BY with HAVING. If you mix up the two filters, write one query that needs both.
- Week 3: window functions. Ranking, running totals and LAG come up again and again. Try Second Highest Salary and Running Total and solve each one two different ways.
- Week 4: timed practice. Do questions you haven't seen, with a timer, and say your approach out loud before you write anything.
Once a week, sit down at a laptop and write a few queries on a full keyboard. Real work usually happens at a full keyboard, and it shows you whether the phone practice carried over.
When a phone app isn't enough
A phone is fine for building the habit and learning the patterns. It's weaker for long queries with several CTEs, for reading big result sets and for practicing a specific engine's syntax. When you reach that point, add a browser site to your routine. Our guide on where to practice SQL compares the free websites and interview prep sites.