Most CRUD applications go the one extra step of putting a uniqueness constraint on the column instead of just relying on the app layer validation, and comparing hidden time stamps on the form if multiple people might edit the same row simultaneously. It’s exceedingly straightforward.

Did you really think thousands of web apps up to and including GitHub and shopify were squeaking by on blind luck? If basic database transactions and integrity weren’t doable in Rails, that’d have had to have been fixed years ago.

Most of your basic questions are covered by the starter Rails Guide for ActiveRecord, eg) transactions, validations, how to add a uniqueness constraint to the DB in a migration

https://guides.rubyonrails.org/active_record_basics.html

The ActiveRecord Queries guide also covers some mechanisms for handling row-level write contention

https://guides.rubyonrails.org/active_record_querying.html#l...