如何在 Rails 3 Active Record Query 中同时选择对象和计数？

发布于 2024-11-17 06:06:25 字数 593 浏览 4 评论 0原文

如何在主动查询中执行类似的操作？

select product.*, count(product_id) AS product_counts
group by(product.*) 
order by product_counts;

我在活动查询中尝试了此操作：

Product.select("product fields, count(product_id) AS product_counts").group("product fields").order(product_counts)

我返回的结果集仅包含按正确计数顺序排序的产品，但没有计数值。我做了一个.to_sql，它返回了正确的sql。

我怎样才能在数据库上保持高效的同时做到这一点或类似的事情？

另一个相关问题是，如何在活动查询中执行 .select("product.*) 或 .group("product.*") ？现在我有列出每个字段，例如 .group("product.id、product.name、product.price...etc")

原文

How do I do something like this in active query?

select product.*, count(product_id) AS product_counts
group by(product.*) 
order by product_counts;

I tried this in active query:

Product.select("product fields, count(product_id) AS product_counts").group("product fields").order(product_counts)

The resultset i get back contains only the products that are sorted in the correct count order, but no count value. I did a .to_sql and it returns the correct sql.

How can I do this or something similar while being efficient on the db?

Another related question is, how do I do a .select("product.*) or .group("product.*") in active query? Right now I have to list every field out, eg. .group("product.id, product.name, product.price...etc")

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各自安好 2024-11-24 06:06:25

@Kevin，

实际上您正在返回product_counts，唯一需要注意的是虚拟属性不会显示在控制台中，因此如果您有：

products = select product.*, count(product_id) AS product_counts
group by(product.*) 
order by product_counts;

#You can access the product_counts just as you would expect
products.first.product_counts

问题2：
不确定你想用 group("product.*") 实现什么，如果你想获得不同的行，你可以在选择中使用 DISTINCT，例如 Product.select("DISTINCT *")

@Kevin,

Actually you are getting back product_counts the only thing to be aware of is that virtual attributes will not be displayed in the console so if you have:

products = select product.*, count(product_id) AS product_counts
group by(product.*) 
order by product_counts;

#You can access the product_counts just as you would expect
products.first.product_counts

Question 2:
Not sure what you are trying to achieve with group("product.*"), if you want to get distinct rows you can use DISTINCT in your select e.g. Product.select("DISTINCT *")

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