Answer 1

The best way to do mysql practice is to use myphpadmin install a sample dB, use php codes to access the dB, and display the data on a webpage, and also store data from web form to dB.

Download a sample database here, https://dev.mysql.com/doc/employee/en/

If you really want to practice mysql query alone, you could visit https://sqlzoo.net, there are tons of tutorials train you up to families with the queries.

Use http://www.sqlfiddle.com/#!9/239940/1 to further test up the mysql queries you wish to test.