Question

我有这样的查询：

answer_histories = AnswerHistory.where(slide_id: self.slide_id)
 .joins(:material_progress).where(material_progresses: {site_id: site.id})
 .joins(:learning_history)
 .where.not("learning_histories.completed_at":nil)    
 .where(MaterialProgress.arel_table[:learning_history_id]
 .eq(AnswerHistory.arel_table[:learning_history_id]))

此查询执行此代码：

SELECT `answer_histories`.* FROM `answer_histories`
INNER JOIN `material_progresses` 
ON `material_progresses`.`id` = `answer_histories`.`material_progress_id`
INNER JOIN `learning_histories`
ON `learning_histories`.`id` = `answer_histories`.`learning_history_id` 
AND `learning_histories`.`deleted_at` IS NULL
WHERE `answer_histories`.`deleted_at` IS NULL
AND `answer_histories`.`slide_id` = 809                                             
AND `material_progresses`.`site_id` = 1

但我想这样：

SELECT `answer_histories`.* FROM `answer_histories`                                             
INNER JOIN `material_progresses` 
ON `material_progresses`.`id` = `answer_histories`.`material_progress_id`                                               
INNER JOIN `learning_histories` 
ON `learning_histories`.`id` = `answer_histories`.`learning_history_id` 
AND `learning_histories`.`deleted_at` IS NULL                                               
**AND `learning_histories`.`completed_at` IS NOT NULL**                                                                     
WHERE `answer_histories`.`deleted_at` IS NULL                                               
AND `answer_histories`.`slide_id` = 809                                             
AND `material_progresses`.`site_id` = 1

如何更改上述查询？

Answer 1

我会做类似的事情：

class LearningHistory < ApplicationRecord
  ...
  scope :completed, ->{ where.not(completed_at: nil) }

然后：

answer_histories = AnswerHistory.where(slide_id: self.slide_id)
 .joins(:material_progress).where(material_progresses: {site_id: site.id})
 .joins(:learning_history)
 .merge(LearningHistory.completed)    
 .where(MaterialProgress.arel_table[:learning_history_id]
 .eq(AnswerHistory.arel_table[:learning_history_id]))

INNER JOIN table1.id = table2.id和col1 = null，col2 = not null

1 个答案: