A practice SQL environment is at https://www.w3schools.com/sql/trysql.asp?filename=trysql_select_all
Note: It is not possible to do these exercises in Firefox. Use Chrome, or if you have a different browser, try it to see if it works.
A series of exercises are described in sql.txt. Create a new git branch called sql-lesson. As you solve each exercise, paste the sql statement you used into sql.txt, and when you have completed all of them, push the result to github and issue a pull request.
You can click on each table in the right hand column to familiarize yourself with the schema of the database. As you solve each of the SQL tasks below, copy the SQL statement and paste it into sql.txt of your git repository using your editor. When you are done with the lesson, push the result to github and issue a pull request.