Beginners problem- having/where

Question

I need to find the model that have maximum number of units
I wrote:
     select model , MODEL_COUNT as model_counter from (
          select model , count (*) as MODEL_COUNT
          from Airplanes     group by model)
          where MODEL_COUNT = max(MODEL_COUNT);
and got:
ORA-00934: group function is not allowed here
So I changed the where to having:
select model , MODEL_COUNT as model_counter from (
          select model , count (*) as MODEL_COUNT
          from Airplanes     group by model)
          having MODEL_COUNT = max(MODEL_COUNT);
and got:
ORA-00979: not a GROUP BY expression
What to do???

Answer 1

Hi and welcome to the forum.
What to do???Well, you could use the row_number analytic here:
select model
,      model_count model_counter
from ( select model
       ,      count (*) model_count
       ,      row_number() over ( order by count(*) desc) rn      
       from airplanes
       group by model
where rn=1;See:
http://www.oracle.com/technology/oramag/oracle/07-jan/o17asktom.html
http://www.oracle.com/technology/oramag/oracle/06-sep/o56asktom.html
for some more in-depth explanations.
And keep in mind that all Oracle Documentation (and examples) can be found @ http://tahiti.oracle.com