About Group By

Question

Hi all,
I have to do a report of services performed by month,
returning the date on format mm/yyyy.
The problem is I must format with to_char,
and the ordinance cannot to be done like Character. It must
to be done per date. I group correctly by the columns,
but in the order by clause I use per date, like this:
SELECT department_id, employee_id
TO_CHAR(service_dt, 'mm/yyyy'), COUNT(*)
FROM services
GROUP BY epartment_id, employee_id
TO_CHAR(service_dt, 'mm/yyyy')
ORDER BY department_id, employee_id
service_dt;But the following error occurs:
ORA-00979: not a GROUP BY expression
How can I do to order by date, but showing in the format mm/yyyy?
thanks !!!!

Answer 1

Then try
SELECT department_id,
       employee_id,
       moyr,
       cnt
FROM (SELECT department_id,
             employee_id,
             TO_CHAR(service_dt, 'mm/yyyy') as moyr,
             COUNT(*) as cnt
      FROM services
      GROUP BY department_id,
               employee_id,
               TO_CHAR(service_dt, 'mm/yyyy')) as inline_view
ORDER BY TO_NUMBER(SUBSTR(moyr, 3, 4)||SUBSTR(moyr, 1, 2))  or just readjust your formatting to be yyyy/mm
SELECT department_id,
       employee_id,
       TO_CHAR(service_dt, 'yyyy/mm') as moyr,
       COUNT(*) as cnt
FROM services
GROUP BY department_id,
         employee_id,
         TO_CHAR(service_dt, 'yyyy/mm')
ORDER BY TO_CHAR(service_dt, 'yyyy/mm')-Chuck