如何将作用域与子查询或 find_by_sql 链接或组合 [英] How to chain or combine scopes with subqueries or find_by_sql

问题描述

我想执行类似的查询

SELECT * FROM ( SELECT * FROM products ORDER BY price ASC ) AS s GROUP BY item;

返回每件商品中最便宜的商品.使用这个子查询很好，因为它可以在 O(N logN) 时间内运行.

which return the cheapest of all products for each item. Using this subquery is good because it can run in O(N logN) time.

所以我可以使用 find_by_sql 找到它，但是能够将它与 Product 的其他作用域链接起来会很好.

So I can find this with find_by_sql, but it would be nice to be able to chain it with other scopes for Product.

有人知道如何将其写为作用域或链式作用域和 find_by_sql 吗?

Anyone know how to either write this as a scope or chain scoped and find_by_sql?

推荐答案

你应该能够做类似的事情

You should be able to do something like

Product.from("(SELECT * FROM products ORDER BY price ASC) AS products").group(:item)

这篇关于如何将作用域与子查询或 find_by_sql 链接或组合的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！