The SQL Playground is a fully client-side relational database workbench powered by SQLite compiled to WebAssembly (WASM). It provides an isolated database engine running directly in your browser tab without requiring server connections, database credentials, or software installation.

### Preloaded Relational Datasets The in-memory SQLite sandbox initializes with four normalized tables ready for querying: - `departments`: Organizational units with `id`, `dept_name`, `budget`, and `location`. - `employees`: Staff records including `id`, `first_name`, `last_name`, `department`, `role`, `salary`, and `hire_date`. - `products`: Inventory items with `id`, `name`, `category`, `price`, and `stock_quantity`. - `orders`: Customer transactions linking `id`, `customer_name`, `product_id`, `quantity`, `order_date`, and `total_amount`.

### Interactive Query Execution & Tool Features - Instant WASM Execution: Executes standard SQLite queries including joins, nested subqueries, CTEs, aggregations (COUNT, SUM, AVG), and window functions with sub-millisecond execution timing. - Interactive Grid & CSV Export: Displays query results in sortable, paginated tables and supports 1-click CSV download. - Visual Join Diagrams: Accompanied by interactive visual Venn diagrams illustrating INNER JOIN, LEFT JOIN, and FULL OUTER JOIN set intersections.

### Practical Query Example To aggregate department headcount and average salary across joined tables: ```sql SELECT d.dept_name, COUNT(e.id) AS headcount, AVG(e.salary) AS avg_salary FROM departments d LEFT JOIN employees e ON d.dept_name = e.department GROUP BY d.dept_name ORDER BY avg_salary DESC; ```

### Zero-Server In-Browser Privacy The entire SQLite database instance exists exclusively in browser memory. No table rows, custom schemas, or executed SQL queries are sent to or logged on any external server.