Question

Using Postgres.

I have users, which have items. Items have a column “type.” I’m trying to get a list of users, that have items, whose item types are not null, and the count of these “not null” items is exactly 1.

Desired query:

select *
from users
join items
where items.type IS NOT NULL
and the count of (items.type IS NOT NULL) == 1

Let me know if there’s any more information I can provide.

Thanks in advance!

Answer 1

select users.id, count(items.type)
from users
join items on items.user_id = user.id
where items.type IS NOT NULL
group by users.id
having count(items.type) = 1