Oracle: how to “group by” over a range?

Question

If I have a table like this:

pkey   age
----   ---
   1     8
   2     5
   3    12
   4    12
   5    22

I can \"group by\" to get a count

Answer 1

Can you try the below solution:

SELECT count (1), '1-10'  where age between 1 and 10
union all 
SELECT count (1), '11-20'  where age between 11 and 20
union all
select count (1), '21+' where age >20
from age