根據記憶年齡篩選團隊的範圍

Question

我有一個模特User，屬性:age和模型Teamhas_many: :users。

我想知道，如何創建2個示波器:same_ages和:different_ages來篩選團隊，或者他們都具有相同的年齡，或者他們有不同的年齡。

Team.same_ages 
# In all teams returned, all members have the same age 

Team.different_ages 
# In all teams returned, there is at least one member with 
# different age as the others 

我怎麼能這樣做？

Answer 1

我只是覺得範圍會像：

scope :same_ages, -> { 
    where("id IN (SELECT team_id 
       FROM users 
       GROUP BY team_id 
       HAVING COUNT(DISTINCT(age)) = 1)" 
} 

scope :different_ages, -> { 
    where("id IN (SELECT team_id 
       FROM users 
       GROUP BY team_id 
       HAVING COUNT(DISTINCT(age)) > 1)" 
}