Rails creates the database tables for whatever ORM you're using using its Migrations. Rails keeps track of which migration files have been run. The usual synta

Rails creates the database tables for whatever ORM you're using using its Migrations. Rails keeps track of which migration files have been run. The usual syntax for creating these migration files is in Ruby, as this makes them database-independent, arguably more easily readable, and in newer versions of Rails, reversible. Of course, you can put plain old SQL in these migrations if you want to as well.