What is the best way to learn SQL to implement it?

Answer 1

take SQL course in Sololearn :)

Answer 2

Install lamp/xampp and use phpmyadmin to practicaally use your db management skills.
When you feel familiar enough, use the command line or an external program to send your queries and manage the db.

Answer 3

Install SQLite, create some tables.

Try the following commands:

select, where, group by, order, join
sub queries