ORA-00979:inte ett GROUP BY-uttryck när jag kör min sql

Problemet är att du beställer efter något som inte finns i din group by klausul.

Detta fungerar till exempel

SQL> with testGroup as ( select 1 as one, 2 as two from dual)
  2  select one
  3  from testGroup
  4  group by one;

       ONE
----------
         1

Om du order by en kolumn som inte finns i din group by klausul:

SQL> with testGroup as ( select 1 as one, 2 as two from dual)
  2  select one
  3  from testGroup
  4  group by two;
select one
       *
ERROR at line 2:
ORA-00979: not a GROUP BY expression

Om du redigerar group by för att hantera kolumnen du behöver i order by :

SQL> with testGroup as ( select 1 as one, 2 as two from dual)
  2  select one
  3  from testGroup
  4  group by one, two;

       ONE
----------
         1

SQL>