To share a certain logic across other examples, let's add a sample SQL
code generated by the given Ruby code

sorry @robin850.
Thanks @fxn

This reverts commit 700c6c65.

Bot the `sqlite3` and `sqlite3-ruby` gems exist.
https://rubygems.org/gems/sqlite3
https://rubygems.org/gems/sqlite3-ruby

In fact, they both point to the same github repository.
https://github.com/luislavena/sqlite3-ruby

However, the last one hasn't been released since 2011, while the first
one keeps getting regular releases.

Add the packages required on Arch Linux when setting up the development
dependencies

for blank?

Rename the I18n keys for associations' restrict_dependent_destroy errors

Removed information about creating database [ci skip]

Rails 4.0 release notes. Explain major features added and removed.

- As default index page is no longer in public folder, rails hits the
  welcome controller in railties for index action
- If the database is not created or username and password are
  incorrect in database.yml, those errors are first shown before index
  action succeeds
- welcome#index succeeds iff the database is created with correct
  details in database.yml
- So this information about creating database is not required in the
  index template

Extract verbs array from helper to a contant

Fix test name typos

Upgrade guide. Renaming Indexes on tables. [ci skip]

https://github.com/rails/rails/commit/39eef1a565ef02e4dabc0811ef1bf4547ff9a60e#commitcomment-3672522

Closes #11498.

remove duplication in concern_test

Revert "Fix SyntaxError in guides sample code"

Thanks @fxn

This reverts commit f573df32.

The original idea of this documentation was to showcase the feature
where you can remove some only queries attributes with a single
key-value pair.

Closes rails/rails#11362

Thanks @egilburg

[ci skip]

[ci skip]

fixes the test case of that plugins

grammar fix in upgrade documentation

Use latest mysql2.