我试图将每个类别的记录限制为 5，但我最终只返回了 5 条记录。
如何在 Rails ActiveRecord 中翻译这条 sql 语句？
SELECT *
FROM "jobs" a
WHERE (
SELECT COUNT(*)
FROM jobs
WHERE ID = a.ID
) <= 5
AND jobkey_confirmation IS NOT NULL
AND EXTRACT(MONTH from created_at) = EXTRACT(MONTH from now())
我只能执行以下操作，如上所述只返回 5 条记录:
scope :confirmed_this_month, where("jobkey_confirmation IS NOT NULL AND EXTRACT(MONTH from created_at) = EXTRACT(MONTH from now())").group("category").limit(5).order("created_at DESC")
最佳答案
可以使用 find_by_sql 吗？
Job.find_by_sql('SELECT * FROM "jobs" a WHERE (SELECT COUNT(*) FROM jobs WHERE ID = a.ID ) <= 5 AND jobkey_confirmation IS NOT NULL AND EXTRACT(MONTH from created_at) = EXTRACT(MONTH from now()))
或者您希望用 AR Calls 完全取代它？
-- 从评论中提取代码----
def self.limited_grouped_jobs
find_by_sql("SELECT * FROM jobs a WHERE (SELECT COUNT(*) FROM jobs WHERE ID = a.ID ) <= 5 AND jobkey_confirmation IS NOT NULL AND EXTRACT(MONTH from created_at) = EXTRACT(MONTH from now())")
end
关于ruby-on-rails - 每组 Rails LIMIT，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/12957459/