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

I guess even this helps:

SELECT
    distinct areas,
    NVL(x.count_item * 100,0) AS Percentage
FROM
    allitems a
    LEFT OUTER JOIN (
        SELECT
            ( COUNT(a.itemid) / (
                SELECT
                    COUNT(*)
                FROM
                    allitems
            ) ) AS count_item,
            areas AS avl_areas
        FROM
            allitems       a
            INNER JOIN currentitems   c ON a.itemid = c.itemid
        GROUP BY
            areas
    ) x ON x.avl_areas = a.areas
;

Answer 2

Just for the heck of it, a way of doing it without analytics.

Jeffrey's solution needed a DISTINCT because of the duplication of areas. The allitems table is actually an intersection table between currentitems and a putative areas table. In the following query this is represented by the inline view ai. There is another inline view tot which gives us the total number number of records in allitems. This count has to be included in the GROUP BY clause, as it is not an aggregating projector.

SQL> select ai.areas
  2         , (count(currentitems.itemid)/tot.cnt) * 100 as "%"
  3  from
  4      ( select count(*) as cnt from allitems ) tot
  5      , ( select distinct areas as areas from allitems ) ai
  6      , currentitems
  7      , allitems
  8  where allitems.areas = ai.areas
  9  and   allitems.itemid = currentitems.itemid(+)
 10  group by ai.areas, tot.cnt
 11  /

AREAS                         %
-------------------- ----------
east                         50
south                        25
west                          0

SQL>

I don't know whether this approach would perform better than Jeffrey's solution: it quite possibly will perform worse (the analytics query certainly has fewer consistent gets). It is interesting simply because it highlights the issues more clearly.

Answer 3

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.

Answer 4

Analytics are your friend:

SELECT DISTINCT
       areas
      ,COUNT(currentitems.itemid)
       OVER (PARTITION BY areas) * 100
       / COUNT(*) OVER () Percentage
FROM allitems, currentitems
WHERE allitems.itemid = currentitems.itemid(+);

Answer 5

A slight modification of your original query :

Select  
areas,
(
Select 
Count(*)
From 
Allitems Inner_Allitems Left Join Currentitems On (Currentitems.Itemid = Inner_Allitems.Itemid) 
Where inner_allitems.areas = outer_allitems.areas
) *100 / (Select Count(*) From allitems ) as percentage
From allitems outer_allitems
Group By areas

Answer 6

Use Group 'By clause':

Select department_id, min(salary)
From employees
Group By department_id
Having min(salary) >
(
    Select min(salary)
    From employees
    Where department_id <> 50
);