About SQL Reference

SQL Reference is a free, independent online documentation project covering 762+ SQL statements, functions, clauses, data types, and operators across 23 categories, from SELECT queries and JOINs to window functions, DDL, and database administration. The goal is simple: every page should answer the questions a developer or data analyst actually has when they look something up — what the syntax is, what each parameter means, what the statement returns, how it behaves on edge cases, and how the major databases (MySQL, PostgreSQL, SQL Server, SQLite, Oracle) differ. Alongside the per-statement reference, the site includes 25 long-form guides and a browser-based SQL playground. Everything runs locally in your browser, there is no account and no paywall, and the content is maintained to track current SQL standards and vendor dialects.