SQL, or Structured Query Language, is a special-purpose programming language designed for managing data held in a relational database management system (RDBMS), or for stream processing in a relational data stream management system (RDSMS).
- Wikibooks: Structured Query Language
- A Gentle Introduction to SQL By Andrew Cumming - School of Computing, Napier University, Edinburgh, UK. 1999-2005 (Available in Albanian, German, Spanish, Chinese, French, Italian and Portuguese)
- SQL Tutorial at 1Keydata.com
- SQL Quick Reference SQL for common statements across SQL-92, Postgres, Sybase, SQL Server, Oracle and MySQL