A function of Ruby on Rails that allows you to handle database data without writing SQL.
This is sometimes called ʻOR mapper.
With Active Record, you can handle data with simple methods without writing SQL statements.
By the way, regardless of Rails, the PHP framework also uses this OR mapper.
User.all
users = User.all
Get information for all users.
User.find
user = User.find(1)
Get the record of the user whose primary key matches.
User.find_by
user = User.find_by(name: 'gorira')
Get the first record that the data in the column matches under the specified conditions.
User.first
user = User.first
Get the first record of the user.
User.where
user = User.where(name: 'takeshi')
Get all records that match the conditions.
User.pluck
users_name = User.pluck(:name)
Get a specific column as an array.
User.order
user = User.order('id DESC')
Sorts based on the specified column.
User.delete_all
user = User.delete_all
Delete all data in the user table.
User.eager_load
user = User.eager_load(:items)
Outer join and get all the data.
https://railsguides.jp/active_record_basics.html
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