This free tool lets you write and run real SQL queries against a small in-browser sample database — three tables (employees, departments, orders) with realistic sample data. Everything runs client-side in your browser; no data is sent anywhere, and no signup or database setup is required.
The playground supports SELECT with column projection or *, FROM a single table, an optional INNER JOIN with an ON condition, an optional WHERE clause with =, !=, >, <, >=, <= comparisons (chainable with AND), an optional ORDER BY with ASC/DESC, and an optional LIMIT. This covers the core clauses used in the large majority of everyday read queries, though it does not implement the full SQL standard (no GROUP BY, subqueries, or multi-table joins beyond one INNER JOIN in this version).
Three tables model a small company: employees (id, name, department_id, salary, hire_year), departments (id, name, budget), and orders (id, employee_id, amount, status). department_id and employee_id are foreign keys, so you can practice INNER JOIN queries connecting employees to their department or their orders.
Reading about SQL syntax is a poor substitute for actually writing and running queries — a sandbox with a small, understandable dataset lets you experiment freely (try a WHERE clause, see if it filters correctly, adjust it) without needing to set up a real database server or risk touching production data. This is the same reason interview prep and SQL courses consistently rely on small sample schemas like this one.
The five example buttons above the editor demonstrate each supported clause: a basic filtered SELECT, LIMIT with ORDER BY, an INNER JOIN across two tables, a WHERE clause combined with a JOIN, and a plain SELECT *. Click any example to load it into the editor and run it immediately, then modify it to explore further.
It is a small, real in-memory JavaScript data structure (plain arrays of objects) queried by a lightweight SQL interpreter written specifically for this tool — not a full database engine like PostgreSQL or SQLite running in the browser. It correctly implements the core SELECT/FROM/JOIN/WHERE/ORDER BY/LIMIT clauses, but it is intentionally a teaching tool, not a production-grade SQL engine.
Not in this version — the schema (employees, departments, orders) is fixed. The goal is a small, consistent, realistic dataset you can learn the core SQL clauses against, similar to the fixed sample schemas used in most SQL courses and interview-prep materials.
The interpreter supports a specific, common subset of SQL syntax. The most common causes of a parse error are: multiple JOINs in one query (only one INNER JOIN is supported), a WHERE clause using OR instead of AND, or a comparison operator other than =, !=, >, <, >=, <=. Simplify the query to the supported clause set and it should parse correctly.
No — the entire tool, including the sample database and the SQL interpreter, runs client-side in your browser as plain JavaScript. Nothing is sent to a server, logged, or stored.