与 mysql 中的 sql_mode=only_full_group_by 不兼容

Question

因此，在将项目从 Rails 3.2 升级到 Rails 4.2 时，不知何故，我的一个模型中的这个查询看起来像：

rows = ActiveRecord::Base.connection.execute("Select q.id,q.times_taken,avg(qr.correct)*100,q.difficulty,q.weight,sk.name,sa.name,sub.name,q.tag_list from 
  (select qu.id,qu.times_taken,qu.difficulty,qu.weight,group_concat(tags.name) tag_list,qu.subject_id,qu.subject_area_id
    from questions qu left join taggings t on (qu.id = taggable_id) left join tags on (t.tag_id = tags.id) 
    where qu.id in (#{@questions_out_ids.join(',')}) and t.taggable_type='Question' group by t.taggable_id) q
  left join subjects sub on (q.subject_id = sub.id) left join subject_areas sa on (q.subject_area_id = sa.id) 
  left join skills_subject_areas ssa on (sa.id = ssa.subject_area_id) left join skills sk on (ssa.skill_id = sk.id), 
  archived_question_results qr,attempts a where  qr.question_id = q.id and a.id = qr.attempt_id and a.is_normalized = 1 
  and a.state = 'complete' group by qr.question_id order by q.id")

已开始产生以下 mysql 错误：

ERROR 1055 (42000): Expression #6 of SELECT list is not in GROUP BY clause and contains nonaggregated column 'faces_development.sk.name' which is not functionally dependent on columns in GROUP BY clause; this is incompatible with sql_mode=only_full_group_by

我查看了类似问题的其他答案，并且我知道我还需要在 GROUP BY 子句中包含某个表的 id 列，但由于我的查询非常复杂，所以我尝试过的选项没有多大用处。我正在使用 gem mysql2 0.3.0 建议？

Answer 1

我想我找到了解决问题的方法，显然是外部select 中的6th 表达式，即sk.name 产生了问题。将相同的表达式添加到外部 group by 子句为我修复了它。

rows = ActiveRecord::Base.connection.execute("select q.id,q.times_taken,avg(qr.correct)*100,q.difficulty,q.weight,sk.name,sa.name,sub.name,q.tag_list from 
  (select qu.id,qu.times_taken,qu.difficulty,qu.weight,group_concat(tags.name) tag_list,qu.subject_id,qu.subject_area_id
    from questions qu left join taggings t on (qu.id = taggable_id) left join tags on (t.tag_id = tags.id) 
    where qu.id in (#{@questions_out_ids.join(',')}) and t.taggable_type='Question' group by t.taggable_id) q
  left join subjects sub on (q.subject_id = sub.id) left join subject_areas sa on (q.subject_area_id = sa.id) 
  left join skills_subject_areas ssa on (sa.id = ssa.subject_area_id) left join skills sk on (ssa.skill_id = sk.id), 
  archived_question_results qr,attempts a where  qr.question_id = q.id and a.id = qr.attempt_id and a.is_normalized = 1 
  and a.state = 'complete' group by sk.name, qr.question_id order by q.id")

Answer 2

config/database.yml:

development: # Or test, or production, or all of them.
  ...
  variables:
    sql_mode: TRADITIONAL

Answer 3

在您的config/database.yml 文件中：

default: &default
  variables:
    sql_mode: TRADITIONAL