Awesome Kata for Beginners, thank you!

This is one of those inmstances where if it had been MySQL I would have gotten it right the first time with SQUARE()...

that's good practice, I do that too

I learned about using commas on the left of the select statements from a DBA I worked with for a few years. He siad it was mainly used with larger datasets, but it allows you to delete the last select without having to also remove the comma on the previous line.

Questions on this Kata:

1. Why use users instead of user as the table name?
2. Is it a better practice on these types of queries to user * or explicitly select "age" and "name"?
3. Why are we constrained to PostgreSQL and not MySQL or MariaDB? (I'm assuming something to do with licensing)