SQL (Structured Query Language) is a standard language for managing and manipulating relational databases. SQL is used to perform various tasks such as inserting, updating, and retrieving data from a database. Here are some useful resources for learning SQL:
W3Schools SQL Tutorial: A comprehensive tutorial on SQL, covering the basics and advanced topics.
https://www.w3schools.com/sql/
SQLBolt - A beginner's tutorial for SQL: A step-by-step tutorial that helps you learn SQL by examples.
https://sqlbolt.com/
SQL Zoo: A series of interactive tutorials that teach you SQL by example.
http://sqlzoo.net/
Mode Analytics SQL Tutorial: A comprehensive SQL tutorial that covers SQL concepts and practices.
https://mode.com/sql-tutorial/
PostgreSQL Tutorial: A tutorial that covers SQL basics, as well as advanced topics such as stored procedures and transactions.
Oracle SQL Tutorial: A tutorial that covers the basics of SQL as well as advanced topics for Oracle database users.
https://docs.oracle.com/en/database/oracle/oracle-database/19/lnpls/index.html
SQLBook.com: A website that provides interactive SQL tutorials and exercises to help you learn SQL.
http://sqlbook.com/
These resources should give you a good starting point for learning SQL. With practice, you'll become proficient in SQL and be able to use it to manipulate and manage databases.