Average after group by in SQL query

Question

select avg(select count(aid)
           from athlete
           group by codepays)

I get a "more than one row error". How with I go about getting the average of the result from my fist select ?

Answer 1

You need to use a table expression (subquery).

For example:

select avg(cnt)
from (
  select count(aid) as cnt
  from athlete
  group by codepays
) x