Rails active record querying association with 'exists'

Question

I am working on an app that allows Members to take a survey (Member has a one to many relationship with Response). Response holds the member_id, question_id, and their answe

Answer 1

You can also use a subquery:

members.where(id: Response.select(:member_id))

In comparison to something with includes it will not load the associated models (which is a performance benefit if you do not need them).