在rails环境中，sql count语句按多列分组

我有两个亲戚（班级）

我明白了

我的目标是在返回结果中同时获得

RecommendTypeFor

的

id

和

name

。目前我只能让它返回

id

或

name

。像这样的

 {{"id" => 1, "name" => "dinner", "count" => 1}, {"id" =>2, "name" => "lunch", "count" => 3} }

---

当然，我可以在获得id或名称后再执行一轮sql来创建该哈希，但我认为这不是有效的方法。感谢您的帮助或建议：）

我相信如果您删除

，请在结尾处计数
，并将
选择更改为：

.select("count(*), recommended_for_type_id, recommended_for_types.name")

您将获得一个模型数组，其中包含您需要的属性和计数

您应该能够通过执行以下操作在控制台中对其进行测试：

 r = RecommendedForTypeRestaurant.where(restaurant_id: rest_id)
 @result =  r.includes(:recommended_for_type)
        .select("recommended_for_type_id, recommended_for_types.name, count(*)")
        .group ("recommended_tor_type_id, recommended_for_types.name")

 @result.each do |r|
     puts r.recommended_for_type_id
     puts r.name
     puts r.count
 end

希望有帮助
 您需要单独分组，请尝试以下分组

.group ("recommended_tor_type_id", "recommended_for_types.name").count

但它似乎真的很慢。
 {{"id" => 1, "name" => "dinner", "count" => 1}, {"id" =>2, "name" => "lunch", "count" => 3} }

.select("count(*), recommended_for_type_id, recommended_for_types.name")

 r = RecommendedForTypeRestaurant.where(restaurant_id: rest_id)
 @result =  r.includes(:recommended_for_type)
        .select("recommended_for_type_id, recommended_for_types.name, count(*)")
        .group ("recommended_tor_type_id, recommended_for_types.name")

 @result.each do |r|
     puts r.recommended_for_type_id
     puts r.name
     puts r.count
 end

.group ("recommended_tor_type_id", "recommended_for_types.name").count