SQL Interview Question Bank with Practice Database and Tested Solutions

For developer, analyst and data interviews with a SQL round: 80 questions with a real SQLite database to run them against, so you practise writing queries instead of memorising answers with no way to check them.

What's inside

• SQL-Interview-Question-Bank-v1.0.zip: practice.db (a SQLite database, a fictional online retail and delivery business with 8 tables, about 2,000 orders and 5,000 order lines), schema.sql and seed_data.sql (rebuild the same database from scratch in SQLite, MySQL or PostgreSQL), questions.md (all 80 questions with hints, solutions and explanations), solutions/Q01.sql to Q80.sql, expected/Q01.csv to Q80.csv (the real output of every solution), check_solutions.py (checks your own answers against the database), and README.md.
• SQL-Interview-Question-Bank.pdf: a 75-page guide with the schema, all 80 questions, hints, solutions, line-by-line explanations and MySQL/PostgreSQL dialect notes, laid out for reading on a laptop or phone.

How to use it

1. Open practice.db in any SQLite 3.25+ client, or read the PDF guide first.
2. Work through the 80 questions, one level at a time, from selects and joins up to window functions and interview classics like gaps-and-islands and cohort retention.
3. Save your attempt as answers/Q07.sql (matching the question number) and run python check_solutions.py to check it against the real database; everything else you have not attempted is still checked against the shipped solutions, so the summary always covers all 80.

Requirements

• Any SQLite 3.25 or later client to open practice.db (window functions and recursive CTEs need 3.25+).
• Python 3.8 or later, standard library only, to run . No installation, account or internet connection needed.