sql group by for counting distinct users

Question

In Postgres I have a properties table with following columns: item, user, property . Each item is unique and belongs to a unique user. Each user can have multiple items. But properties are not uniques, ie, the same property can be the same for many items. eg,

item, user, property
--------------------
item1 user1 property1
item1 user1 property2
item2 user1 property1
item2 user1 property3
item2 user1 property4
item3 user2 property2
item3 user2 property4

Now I want to calculate how many unique users have the given property in their items, ie, in this case I need to get:

property1 1
property2 2
property3 1
property4 2

I can think of an SQL query for that like this:

SELECT COUNT(*), x.property
FROM (SELECT user, property
      FROM properties
      GROUP BY user, property) x
GROUP BY x.property;

Is there a better way to do this? Thanks!

Answer 1

select count(distinct user), property
from properties
group by property

sql fiddle demo