Active Record查询中的条件

Question

I have a large database of information. They are mostly patients. Some of them have email addresses and some of them don't. I can pull an additional email address by simply running

Patient.last.email

However I only want to see the patients who do not have email addresses. (I think its about half of the ones that I have)

I've tried both these below, but not having the best of luck.

Patient.includes(:email).where('email = ?', 'nil')
Patient.includes(:email).where('email = ?' 'nil').references(:email)

Would anyone know what I'm doing wrong?

Answer 1

Simple then.

Patient.where(email: nil)

Should get you your result.