SQL Playground — Run SQL in Your Browser

📅 SQL (SQLite)

-- Welcome to the SQL playground!
-- Press Run (or Ctrl+Enter) to execute.
-- Each Run starts a fresh in-memory database.

-- 1. Create tables
CREATE TABLE departments (
  id   INTEGER PRIMARY KEY,
  name TEXT NOT NULL
);

CREATE TABLE employees (
  id            INTEGER PRIMARY KEY,
  name          TEXT    NOT NULL,
  department_id INTEGER REFERENCES departments(id),
  salary        REAL    NOT NULL,
  hire_date     TEXT    NOT NULL
);

-- 2. Insert data
INSERT INTO departments VALUES (1, 'Engineering'), (2, 'Marketing'), (3, 'Finance');

INSERT INTO employees VALUES
  (1, 'Ada Lovelace',   1, 95000, '2022-03-15'),
  (2, 'Grace Hopper',   1, 98000, '2021-06-01'),
  (3, 'Alan Turing',    1, 92000, '2023-01-10'),
  (4, 'Claude Shannon', 2, 85000, '2022-09-20'),
  (5, 'Emmy Noether',   2, 88000, '2021-11-05'),
  (6, 'Lise Meitner',   3, 91000, '2020-04-12');

-- 3. Query with JOIN
SELECT
  e.name,
  d.name  AS department,
  e.salary,
  e.hire_date
FROM employees e
JOIN departments d ON e.department_id = d.id
ORDER BY e.salary DESC;

-- 4. Aggregate by department
SELECT
  d.name              AS department,
  COUNT(*)            AS headcount,
  ROUND(AVG(e.salary)) AS avg_salary,
  MAX(e.salary)       AS top_salary
FROM employees e
JOIN departments d ON e.department_id = d.id
GROUP BY d.id
ORDER BY avg_salary DESC;

Results

Press Run to load SQLite and execute…

Ctrl+Enter to run · Database resets on each Run · First run loads sql.js (~1MB, cached after)

Try these examples

Click any example to load it, then hit Run.

How this works

sql.js is SQLite — the world's most-used database engine — compiled to WebAssembly. When you press Run for the first time, the browser downloads sql.js (~1MB) and caches it. Every subsequent run is instant.

Each Run creates a fresh in-memory database, executes your SQL statements one by one, and displays SELECT results as formatted tables. Non-SELECT statements (CREATE, INSERT, UPDATE, DELETE) show a ✓ confirmation. Errors show in red with the SQLite error message.

SQLite vs other databases: SQLite supports standard SQL — SELECT, INSERT, UPDATE, DELETE, JOIN, GROUP BY, HAVING, subqueries, CTEs, window functions, and transactions. A few things are different from PostgreSQL or MySQL: data types are flexible, there's no native BOOLEAN (use 0/1), and some advanced features (e.g. RIGHT JOIN) aren't supported.

What to try next

SQL language reference — deep dives on JOINs, indexes, transactions, and query planning
SQL snippets — 15 copy-ready patterns for common queries
Python playground — combine Python logic with SQL data
JavaScript playground — JS array methods as an alternative mental model