Remedy for "Uniqueness validator will no longer enforce case sensitive comparison in Rails 6.1."

Regarding the content

――Mr. Ito, who is famous for cherry books, has written a very easy-to-understand article, so please have a look there. - https://qiita.com/jnchito/items/e23b1facc72bd86234b6

solution

--For Rails, you don't have to execute queries or change MySQL settings! Just rewrite it as follows! --Note that the changes will not be reflected if you use rails db: reset! --Execute rails db: drop and rails db: create --Maybe you can also use rails db: migrate: reset.

config/database.yml

default: &default
  adapter: mysql2
  encoding: utf8mb4
  charset: utf8mb4 #Postscript
  collation: utf8mb4_bin #Postscript
  reconnect: false