Ruby on rails rubyonrails中多表的join操作

在我的postgresql数据库中有三个表，分别名为“审计”、“位置”、“公司”

我想通过连接这些表来检索数据。我有一个可执行的sql查询，它给出了我的预期结果。我想将其转换为ruby on rails

select a.name as cname, b.name as lname, count(c.company_id) as count
from companies as a, locations as b, audits as c
where a.id=c.company_id and b.id =c.location_id
group by a.name,b.name;

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我将尝试从您的查询中重新创建模型（我可能会弄错，所以您也应该将其粘贴到查询中）：

因此，要重新创建查询，请执行以下操作：

Company.joins(:locations, :audits)
  .group("companies.name", "locations.name")
  .count("audits.company_id")

结果将是一个散列，其中键是由公司名称和位置名称组成的数组，值是如下所示的计数：

{[company_name, location_name] => count, ...}

这将导致以下查询：

SELECT COUNT(audits.company_id) AS count_audits_company_id, companies.name AS companies_name, locations.name AS locations_name 
FROM "companies" INNER JOIN "locations" ON "locations"."company_id" = "companies"."id"
INNER JOIN "audits" ON "audits"."company_id" = "companies"."id" 
GROUP BY companies.name, locations.name

更多信息

SELECT COUNT(audits.company_id) AS count_audits_company_id, companies.name AS companies_name, locations.name AS locations_name 
FROM "companies" INNER JOIN "locations" ON "locations"."company_id" = "companies"."id"
INNER JOIN "audits" ON "audits"."company_id" = "companies"."id" 
GROUP BY companies.name, locations.name