加入与活跃记录的多个表 [英] Join multiple tables with active records

问题描述

我想知道坐落在一个曾孙标签的旗号。下面是我的数据库是：

I want to know the banner name situated in a great grandchildren tab. Here's how my data base is:

Inscription (where I need to start from): Item1_id
Item1: Item2_id
Item2: Banner_id
Banners: name

如何让我的题词表的所有横幅名的活动记录？

How do i get all the banners name of my inscription table with active records?

推荐答案

您可以执行以下操作：

Inscription.includes(item1: { item2: :banner })

的关系名称 ITEM1 ，项目2 和横幅需要匹配给每个关系的名称

The relations names item1, item2 and banner need to match the names given to each relation.

如果你想在这个查询设置了其中，语句，你可以这样做：

If you want to set a where statement on this query, you can do:

scope = Inscription.includes(item1: { item2: :banner }) 
scope = scope.where(banner: { name: "MOTD: Hello World!" })
scope = scope.where(item2: { is_favorite: true })

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