🗄️ Database testing practice
SQL Playground
37 exercises from your first SELECT to window functions, CTEs, DELETE and UPDATE — the queries testers get asked in interviews. Write a query, press Run, and it's checked instantly.
Runs in your browser with SQLite (sql.js) · nothing to install · every run starts from fresh data · progress saved on this device.
Fresher
Your first SELECT
List every employee's name and salary.
or Ctrl/⌘ + Enter
🗂 Tables
Every run starts from this data, so you can't break anything — go ahead and try DELETE or UPDATE.
- (id, name)4 rows — HR has nobody in it
- (id, name, dept_id, manager_id, salary)8 rows — Kabir has no department and no salary
- (id, name, email)5 rows — one email appears twice, one is in capitals
- (id, customer_id, amount, created_at)6 rows — order 4 is a guest checkout (customer_id is NULL)
The answers explained: Database & SQL interview questions. SQLite is close to standard SQL; where MySQL, PostgreSQL, SQL Server or Oracle differ, those answers say so.