SQL Useful links

Online SQL Editors & Practice Tools

• SQL Fiddle

  
  

  Test and share SQL queries online with schema setup. Supports MySQL, PostgreSQL, SQLite, etc.

• DB Fiddle

  
  

  Write and test SQL for various databases. Good for comparing behavior across DBMS.

• SQLite Online

  
  

  Run SQLite queries in-browser. No account or installation required.

• Hackerrank – SQL Domain

  Guided challenges with solutions and leaderboard. Excellent for interview preparation.

Reference Documentation

• MySQL Official Docs

  
  

  Full documentation on MySQL server, syntax, and functions.

• PostgreSQL Official Docs

  
  

  Authoritative source for PostgreSQL syntax and features.

• SQL Server (Microsoft) Docs

  
  

  In-depth reference for T-SQL and SQL Server features.

• Oracle SQL Documentation

  
  

  Comprehensive guide for Oracle SQL syntax and best practices.

Cheat Sheets

• SQL Cheat Sheet by DataCamp

  
  

  Summarizes key SQL commands and functions in one PDF.

• SQL Cheat Sheet by Cheatography

  
  

  Handy reference for SQL clauses, functions, and syntax.