Trying to learn complex SQL Queries and active record include/joins

I am looking for rails app examples or sql database examples that I can
use to play around with. I am interested in increasing my proficiency
complex SQL joins, subqueries and the like as well as complex queries
through active record join/include … Any suggested samples, please let
know thanks

Are you proficient with complex SQL… ? Do you have a database against
which you can test? Do you have database needs in mind toward seeking
Rails ActiveRecord? Then my suggestion is that you take some time to
explore the Rails ActiveRecord API. Google Rails ActiveRecord API.
your time… And there is, of course, GitHub… Thousands of