Question

我想用第一个模型的联接和位置将查询链接起来

FbGroup.joins(:fb_posts).where(id: [1,2])
# this returns a lot of extra rows

FbGroup.joins(:fb_posts).where('fb_groups.id IN (?)', acct_ids)
# also tried this with no luck

在进行联接时，如何首先按具有特定ID的fb_groups进行过滤？

Answer 1

仅同时使用这两种方法是否奏效？

alter table t add email_id int;

update t join
       (select email, row_number() over (order by email) as rn
        from (select distinct email from t order by email) t 
       ) tt
       on t.email = tt.email
    set t.email_id = tt.rn;

您也可以使用的PS

FbGroups.joins(:fb_groups).where(id: [1,2]).where('fb_groups.id IN (?)', acct_ids)

或者，因为两个FbGroups.joins(:fb_groups).where(id: [1,2]).where(fb_groups: {id: acct_ids})现在都使用哈希参数：

where

Answer 2

FbGroup.distinct.joins(:fb_posts).where
              .not(id: FbGroup.joins(:fb_posts)
                       .where(fb_groups: {id: [1,2]}).distinct)

ActiveRecord加入自己的id数组

2 个答案: