Ruby/rails/dbモデル

table本体クラス

例：user (app/models/user.rb)

class User < ApplicationRecord
end

ApplicationRecordを継承する

検索

users = User.find(1)
users = User.find_by(email: "test@example.com")
users = User.where("email = ?", "test@example.com")
users = User.where("email = :email", email: "test@example.com") # こちらの方が可読性が良い

２つ条件をつけ検索

users = User.where("name = :name", name: "taro")
                 .where(del_flag: false)

順序

users = User.order(:created_at)

件数

users = User.limit(5)

group by

users = User.select("date, sum(date)").group("date")

特定カラムのみ

users = User.select("name, created_at")

insert

user = User.new(name: "taro", email: "test@example.com")
user.save

or

user = User.create(name: "taro", email: "test@example.com")

保存

user = User.find(1)
user.name = "taro"
user.save

削除

user = User.find(1)
user.destroy