SQL, or Structured Query Language, is a standard language for managing data held in relational database management systems. Here are some resources that can help you learn and master SQL.

1. Oracle Live SQL

   Oracle Live SQL is an interactive platform provided by Oracle that allows you to run SQL queries, scripts, and model data structures. It’s a great resource for beginners and experienced users alike.

2. LeetCode

   LeetCode is known as the world’s leading online programming learning platform, LeetCode offers a vast collection of SQL problems for different difficulty levels, making it a perfect place to practice.

3. SQL Police Department

   sqlpd.com is a unique and fun way to learn SQL. Here, you solve crimes using SQL queries, which makes the learning process engaging.

4. SQLZoo

   SQLZoo offers interactive SQL tutorials where you can learn SQL by doing. It covers a wide range of topics from basic to advanced SQL.

5. SQLBolt

   SQLBolt provides a set of interactive lessons and exercises designed to help you quickly learn SQL right in your browser.

6. The SQL Murder Mystery

   knightlab.com is a murder mystery game where you use SQL to uncover clues and solve the crime. It’s a fun and engaging way to practice SQL.

7. SQLFiddle

   sqlfiddle.com is a free AI-enhanced online SQL Server compiler for learning and practice. It allows you to create, run, and share SQL queries.

8. SQL Island

   SQL Island (uni-kl.de) is a adventure game for learning SQL. You are stranded on an island and need to use SQL to interact with the local inhabitants and complete tasks.

9. DataLemur

   datalemur.com offers a free SQL tutorial specifically designed for data analysts and data scientists. It covers SQL basics as well as advanced topics like joins, subqueries, and functions.

10. BigTechInterviews

    BigTechInterviews is a platform that provides real interview questions from big tech companies. It’s a great resource to prepare for SQL-related job interviews.