In the terminal, select the directory you want to create the application with "cd ~". rails _ 6.0.0 _ new (name of the application you want to create) -d If you enter mysql and "Webpacker successfully installed" is displayed after many "create ~" are displayed, it is successful. rails new is a command that rails, a ruby framework, creates a set of files required for a web application.
If you get an error, 「bundle config --delete build.mysql2」 「bundle config --global build.mysql2 --with-opt-dir="$(brew --prefix openssl)"」 "Cd ~ (created app name)" I think it's okay if you type "bundle install" in order.
If you enter cd (name of the created app), you can move to the directory of that app and add a library.
After that, I think that "encoding: utf8mb4" is described in about the 14th line of config / database.yml of (created application name) with VS Code etc. Delete "mb4" of "utf8 mb4" and change it to "encoding: utf8". Go to the terminal and type rails db: create "Created database'(created app name) _development'" I think that two of "Created database'(created application name) _test'" are displayed. After entering rails s, enter "localhost 3000" on the web, and if you see an illustration of people from all over the world on the earth under "Yay! You're on Rails!", You are successful.
Since I am a beginner, I would appreciate it if you could point out any mistakes.