Question

I have this query:

select count(*) from logins group by user_id

this returns me the user logins number for each user:

Count(*)

---

10

23

35

54

With a single and efficient query, how can select (calculate) the medium value of this? medium = (10+23+35+54)/4.

Answer 1

select avg(num_login) 
  from (select count(*) as num_login 
  from logins group by user_id) as num_logins