Question

I have a table like this

column1 column2 column3

abc      xyz      4
def      ghi      3
abc      xyz      6
abc      xyz      1
jkl      mno      4

Expected Result after query

column1 column2 column3

abc      xyz      11
def      ghi      3
jkl      mno      4

My Query is like below:

select column1, column2, count(column3)
from
    (select ......) as column1, 
    (select ......) as column2, 
    (select ......) as column3) 
group by column1, column2, count(column3)

I get this error “not a single-group group function”

Answer 1

You need to use SUM and you must remove the count(column3) in the group by and if you really get the columns as results from sub-queries it might need to rather look like this:

select column1, column2, sum(column3) 
from   (
         select
             (select ......) as column1, 
             (select ......) as column2, 
             (select ......) as column3
           from dual
       )
group by column1, column2

otherwise you would need to repeat the entirety of the sub-query select in the group by. In your query you say FROM (select .......) as column1 but that means that the subquery is called column1 which does not work. The selected columns in the subquery could be addressed by using the prefix column1. For example if you say FROM (select x from test) t1 then you can address x by writing t1.x.

but if you have a simple table as you describe above the correct statement is

select   column1, column2, sum(column3) from mytable
group by column1, column2