Ruby on rails Rails 3在一个查询中包含多个表

我正在为锦标赛开发rails应用程序。我在这个查询中使用了三种模型：

class Player < ActiveRecord::Base
  validates :name, :uniqueness => true
  has_and_belongs_to_many :tournaments

class Tournament < ActiveRecord::Base
  belongs_to :tournament_type
  has_and_belongs_to_many :players
  has_many :player_matches, :dependent => :destroy

class PlayerMatch < ActiveRecord::Base
  belongs_to :player_one, :class_name => "Player", :foreign_key => "player_one"
  belongs_to :player_two, :class_name => "Player", :foreign_key => "player_two"

虽然锦标赛和玩家_比赛在单个连接中完成，但会单独查询玩家，因为我的代码依赖于他们：

Player Load (0.4ms)  SELECT `players`.*, t0.tournament_id as the_parent_record_id FROM `players` INNER JOIN `players_tournaments` t0 ON `players`.id = t0.player_id WHERE (t0.tournament_id = 14)
Player Load (0.2ms)  SELECT `players`.* FROM `players` WHERE `players`.`id` = 5 LIMIT 1
Player Load (0.2ms)  SELECT `players`.* FROM `players` WHERE `players`.`id` = 9 LIMIT 1
Player Load (0.2ms)  SELECT `players`.* FROM `players` WHERE `players`.`id` = 1 LIMIT 1
Player Load (0.1ms)  SELECT `players`.* FROM `players` WHERE `players`.`id` = 8 LIMIT 1
Player Load (0.1ms)  SELECT `players`.* FROM `players` WHERE `players`.`id` = 3 LIMIT 1
Player Load (0.1ms)  SELECT `players`.* FROM `players` WHERE `players`.`id` = 2 LIMIT 1
Player Load (0.1ms)  SELECT `players`.* FROM `players` WHERE `players`.`id` = 7 LIMIT 1
Player Load (0.1ms)  SELECT `players`.* FROM `players` WHERE `players`.`id` = 6 LIMIT 1
Player Load (0.1ms)  SELECT `players`.* FROM `players` WHERE `players`.`id` = 4 LIMIT 1

我怎样才能将其更改为一个查询？

锦标赛。其中（：id=>params[:id]）。包括（[{:player\u matches=>：player\u one}，：players]）。first（）

---

这应该能奏效。实际上，数组表示法和散列表示法的组合在一开始排序时有点混乱，但是使用控制台，您会发现哪种语法不会崩溃：）

将其作为注释扔掉，因为类似的东西修复了我的N+1问题，但我不确定它是否适用于您。如果您将

includes

调用更改为

includes（：player\u matches=>：players）

，您会得到什么结果？另外，将其丢弃。。。确保您查看的是生产模式中使用的SQL，而不是开发模式。您尚未在生产模式中运行此SQL。该输出来自终端中的服务器控制台，与日志一样，因此我知道我有正确的输出：）。我复制了Rails 3.0.3的确切设置，但没有得到相同的输出。第一个“玩家加载”行是一次加载所有玩家的行，也是我得到的唯一一个。您的输出真的仅仅是执行那一行代码吗？我的猜测是，在你看来，你是在循环浏览玩家。我会关闭您的服务器，打开Rails控制台，并在development.log中查看SQL时执行这一行。是的，我有一个集合，它已传递给一个分部。然后部分循环通过它。感谢您的回复。不过，我仍然会收到多个播放器的查询：（。我想知道我的问题是否在于如何使用数据，或者数据库的结构如何。

Player Load (0.4ms)  SELECT `players`.*, t0.tournament_id as the_parent_record_id FROM `players` INNER JOIN `players_tournaments` t0 ON `players`.id = t0.player_id WHERE (t0.tournament_id = 14)
Player Load (0.2ms)  SELECT `players`.* FROM `players` WHERE `players`.`id` = 5 LIMIT 1
Player Load (0.2ms)  SELECT `players`.* FROM `players` WHERE `players`.`id` = 9 LIMIT 1
Player Load (0.2ms)  SELECT `players`.* FROM `players` WHERE `players`.`id` = 1 LIMIT 1
Player Load (0.1ms)  SELECT `players`.* FROM `players` WHERE `players`.`id` = 8 LIMIT 1
Player Load (0.1ms)  SELECT `players`.* FROM `players` WHERE `players`.`id` = 3 LIMIT 1
Player Load (0.1ms)  SELECT `players`.* FROM `players` WHERE `players`.`id` = 2 LIMIT 1
Player Load (0.1ms)  SELECT `players`.* FROM `players` WHERE `players`.`id` = 7 LIMIT 1
Player Load (0.1ms)  SELECT `players`.* FROM `players` WHERE `players`.`id` = 6 LIMIT 1
Player Load (0.1ms)  SELECT `players`.* FROM `players` WHERE `players`.`id` = 4 LIMIT 1