轨道3：阿雷尔为NOT EXISTS？ [英] Rails 3: Arel for NOT EXISTS?

问题描述

你怎么写 NOT EXISTS 在阿雷尔？我有麻烦翻译此查询到阿雷尔：

  SELECT * FROM交易
WHERE NOT EXISTS（
   SELECT 1 FROM reward_deals
   WHERE reward_deals.deal_id = deal.id
   AND NOT（
      reward_deals.awarding_type =交易
      与reward_deals.deal_id = reward_deals.awarding_id
   ）
 ）
 

解决方案

下面就是答案，用奇怪的名字，因为我不知道怎么给名称的域对我来说未知。

 交易= Deal.arel_table
reward_deals = RewardDeal.arel_table
awarding_condition = reward_deals [：awarding_type] .EQ（交易）\
                                。而（reward_deals [：deal_id] \
                                       .EQ（reward_deals [：awarding_id]））

reward_deals_condition = reward_deals [：deal_id] .EQ（交易[：ID]）\
                              。而（awarding_condition.not）
Deal.where（RewardDeal.where（reward_deals_condition）.exists.not）
 

问候， 佩德罗

How do you write a NOT EXISTS in Arel? I'm having trouble translating this query into Arel:

SELECT * FROM deals 
WHERE NOT EXISTS (
   SELECT 1 FROM reward_deals 
   WHERE reward_deals.deal_id = deal.id 
   AND NOT (
      reward_deals.awarding_type = 'deal' 
      AND reward_deals.deal_id = reward_deals.awarding_id
   )
 )

解决方案

Here is the answer, with strange names because I don't know how to give names for a domain that is for me unkown.

deals = Deal.arel_table
reward_deals = RewardDeal.arel_table
awarding_condition= reward_deals[:awarding_type].eq('deal')\
                                .and(reward_deals[:deal_id]\
                                       .eq(reward_deals[:awarding_id]))

reward_deals_condition= reward_deals[:deal_id].eq(deals[:id])\
                              .and(awarding_condition.not)
Deal.where(RewardDeal.where(reward_deals_condition).exists.not)

Greetings, Pedro

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