SQL Editor

About the SQLMentor editor

The SQLMentor editor runs queries entirely in your browser using sql.js — SQLite compiled to WebAssembly. There's no server round-trip, no signup, and no data leaves your machine. It's the fastest way to practise SQL on a real schema without installing Oracle, PostgreSQL, MySQL or SQL Server locally.

Supported dialects

The editor simulates four dialects: Oracle SQL, MySQL, PostgreSQL, and Microsoft SQL Server (T-SQL). Dialect-specific syntax (like Oracle's ROWNUM, PostgreSQL's :: casts, or T-SQL's TOP n) is translated to SQLite-compatible SQL on the fly. All four share a common Oracle HR schema so you can compare dialects on the same data.

The HR sample schema

Eleven tables ship pre-loaded: employees, departments, jobs, job_history, locations, countries, regions, dependents, salaries, projects, and project_assignments. The schema is rich enough to practise joins, subqueries, CTEs, window functions, and aggregation without contrived examples.

Tips for getting the most out of the editor

• Press Ctrl+Enter to run the current query.
• Use the Quick examples chips below the editor to load common patterns.
• Switch dialects to see how the same logic renders in Oracle, MySQL, PostgreSQL, and T-SQL.
• The schema cards at the bottom of the page show every column — handy when writing joins.
• For deeper learning, jump to the Oracle SQL tutorial or the PostgreSQL tutorial.