Ruby on rails 如何基于关联的模型条件进行查询?
我有以下资料:Ruby on rails 如何基于关联的模型条件进行查询?,ruby-on-rails,ruby-on-rails-3,postgresql,Ruby On Rails,Ruby On Rails 3,Postgresql,我有以下资料: Groups: id, title GroupMembers: id, group_id, name 组有许多组成员 如何查询数据库以获取至少有2个GroupMember的所有组 谢谢试试这个: Group.joins("( SELECT group_id FROM group_members GROUP BY group_id HAVING COUNT(1) > 1 ) a ON a.member_id = groups.id")
Groups: id, title
GroupMembers: id, group_id, name
组有许多组成员
如何查询数据库以获取至少有2个GroupMember的所有组
谢谢试试这个:
Group.joins("(
SELECT group_id
FROM group_members
GROUP BY group_id
HAVING COUNT(1) > 1
) a ON a.member_id = groups.id")