How to resolve ORA-00937: not a single-group group function when calculating percentage?

Question

I\'m trying to get a percentage of the itemid that are available in a certain area. Using my query, I get an error ORA-00937: not a single-group group function<

Answer 1

Here is a quick first pass:

select ai.areas,
       (sum(cnt) / max(tot)) * 100 "Percentage Result"
  from (select ai.itemid,
               ai.areas,
               count(ci.itemid) cnt,
               count(ai.areas) over () tot
          from allitems ai
               left outer join
               currentitems ci on (ai.itemid = ci.itemid)
        group by ai.itemid, ai.areas
       ) ai
group by ai.areas

Also, in your test data your itemid 4 needs to be changed to west.