Comprehensive SQL practice — 135 interactive questions
Choose a topic and start practicing: one question at a time — write a query and actually run it on a real database in the browser, or answer a multiple-choice quiz with a full explanation. 135 questions from easy to hard, free and with no installation required.
What you will find in the comprehensive practice
The comprehensive practice lets you practice SQL queries Directly in the browser — without installing a database. Every query runs on an engine SQLite real, gets a score, and comes with a sample solution and explanation.
- SELECT and filtering: Selecting columns, WHERE, DISTINCT, LIKE, IN, BETWEEN.
- Sorting and limiting: ORDER BY, LIMIT, OFFSET.
- Grouping and aggregation: GROUP BY, HAVING, COUNT, SUM, AVG, MIN, MAX.
- JOIN: INNER and LEFT JOIN, anti-join, and tricky joins.
- advanced: Subqueries, CASE, window functions (ROW_NUMBER, RANK, DENSE_RANK).
- Text and date: UPPER/LOWER, TRIM, REPLACE, strftime, and more.
- Interview prep: Common SQL questions in data analyst job interviews, by difficulty level.
Who the practice is suited for
For everyone learning SQL from scratch, for students, and for job seekers preparing forData analyst interview (Data Analyst). The questions are arranged from easy to hard, so you can progress gradually.
The practice database
The practice is done on a database with 14 linked tables — employees, departments, attendance, orders, order items, products, suppliers, categories, customers and payments — and it has up to 30,000 records. You can view the full structure and the relationship diagram (ERD) from within the exercise.
Frequently Asked Questions
Is the practice free?
Yes. Use is completely free, with no sign-up and no payment.
Do you need to install software or a database?
No. The SQLite engine runs directly in the browser (sql.js), — so you can write and run real queries with no installation at all.
Which SQL topics are included in the practice?
SELECT, filtering with WHERE, sorting and limiting, GROUP BY and aggregations, JOIN types, subqueries, window functions like ROW_NUMBER and RANK, and text and date functions.
Is the practice suitable for preparing for a data analyst job interview?
Yes. There are dedicated categories of common SQL interview questions, organized by difficulty level.
How many questions are in the practice?
135 questions, 76 of them queries you run in the SQL editor, arranged from easy to hard.
Which database are we practicing on?
A database with 14 linked tables (employees, departments, orders, products, customers, and more) with up to 30,000 records.