Ruby on rails 联接子查询中的计数和求和-我可以使用ActiveRecord构建此sql查询吗？

我正在学习ActiveRecord。我可以建立这个查询吗

    @sales_by_product = ActiveRecord::Base.connection.execute("SELECT
    it.name,
    it.id,
    it.seller_id,
    pur.volume,
    pur.sales
    FROM items it
    INNER JOIN (SELECT
        item_id,
        COUNT(*) AS volume,
        SUM(price) AS sales,
        workflow_state AS state
        FROM purchases
        WHERE workflow_state = 'payment_successful'
        GROUP BY item_id,
        workflow_state) pur
    ON pur.item_id = it.id
    WHERE it.seller_id = '" + current_user.id.to_s + "'")

我希望尽可能多地使用AR api，但我还没有让上面的内容只使用AR

---

谢谢

我认为在这个查询中使用AR不是一个好主意。一开始似乎很有趣，但后来变得很烦人。而且，以后很难改变

您可以创建自己的查询生成器：

def query_for current_user
  <<-SQL
    SELECT
      it.name,
      it.id,
      it.seller_id,
      pur.volume,
      pur.sales
      FROM items it
      INNER JOIN (SELECT
        item_id,
        COUNT(*) AS volume,
        SUM(price) AS sales,
        workflow_state AS state
        FROM purchases
        WHERE workflow_state = 'payment_successful'
        GROUP BY item_id,
        workflow_state) pur
      ON pur.item_id = it.id
      WHERE it.seller_id = '" + current_user.id.to_s + "'")
  SQL
end

@sales_by_product = ActiveRecord::Base.connection.execute( query_for( current_user ))

def query\u用于当前用户
ActiveRecord是一个很好的ORM，但有时您希望直接编写原始sql。它更直接，更精确。我认为ActiveRecord有它的局限性……也许您可以描述一下sql语句应该返回什么，以帮助我们帮助您。