2.4.0 :007 > ReqCity.joins(:cities).select("cities.city")
  ReqCity Load (0.4ms)  SELECT  cities.city FROM "req_cities" INNER JOIN "cities" ON "cities"."req_city_id" = "req_cities"."id" LIMIT ?  [["LIMIT", 11]]
ActiveRecord::StatementInvalid: SQLite3::SQLException: no such column: cities.req_city_id: SELECT  cities.city FROM "req_cities" INNER JOIN "cities" ON "cities"."req_city_id" = "req_cities"."id" LIMIT ?

➜  db git:(master) ✗ sqlite3 development.sqlite3
SQLite version 3.16.0 2016-11-04 19:09:39
Enter ".help" for usage hints.
sqlite> .schema
CREATE TABLE "schema_migrations" ("version" varchar NOT NULL PRIMARY KEY);
CREATE TABLE "ar_internal_metadata" ("key" varchar NOT NULL PRIMARY KEY, "value" varchar, "created_at" datetime NOT NULL, "updated_at" datetime NOT NULL);
CREATE TABLE "users" ("id" INTEGER PRIMARY KEY AUTOINCREMENT NOT NULL, "email" varchar, "created_at" datetime NOT NULL, "updated_at" datetime NOT NULL, "password_digest" varchar, "job_titles_id" integer, "admin" boolean DEFAULT 'f', "remember_digest" varchar);
CREATE UNIQUE INDEX "index_users_on_email" ON "users" ("email");
CREATE TABLE "job_titles" ("id" INTEGER PRIMARY KEY AUTOINCREMENT NOT NULL, "job_title" varchar, "created_at" datetime NOT NULL, "updated_at" datetime NOT NULL);
CREATE INDEX "index_users_on_job_titles_id" ON "users" ("job_titles_id");
CREATE TABLE "requirements" ("id" INTEGER PRIMARY KEY AUTOINCREMENT NOT NULL, "name" varchar, "created_at" datetime NOT NULL, "updated_at" datetime NOT NULL);
CREATE TABLE "cities" ("id" INTEGER PRIMARY KEY AUTOINCREMENT NOT NULL, "city" varchar, "created_at" datetime NOT NULL, "updated_at" datetime NOT NULL);
CREATE TABLE "req_cities" ("id" INTEGER PRIMARY KEY AUTOINCREMENT NOT NULL, "requirement_id" integer, "city_id" integer);

class ReqCity < ApplicationRecord
    has_many :requirements
    has_many :cities
end


class Requirement < ApplicationRecord
    has_and_belongs_to_many :cities
end

class City < ApplicationRecord
    has_and_belongs_to_many :requirements
end


# MIGRATION

class CreateReqCities < ActiveRecord::Migration[5.1]
  def change
    create_table :req_cities do |t|
    end
    add_column :req_cities, :requirement_id, :integer
    add_column :req_cities, :city_id, :integer
  end
end

I would like to based on requirement_id in req_cities display a proper city... based on city_id. How to do it?