USAGE OF GROUP BY CLAUSE

How we use  wdj.PLAN_MAINTENANCE  with SELECT Where as i dont  to want  it with  GROUP BY ?

SELECT cdv.DEPARTMENT_CODE Sum_Dept, 
               cdv.RESOURCE_CODE        Sum_Resource,
               wdj.PLAN_MAINTENANCE,
               CASE wdj.PLAN_MAINTENANCE WHEN  'Y' THEN SUM(cdv.TRANSACTION_QUANTITY)  END SUM_PLAN,
               CASE wdj.PLAN_MAINTENANCE WHEN  'N' THEN SUM(cdv.TRANSACTION_QUANTITY)  END SUM_UPLAN

   ----             SUM(cdv.TRANSACTION_QUANTITY)   Sum_Hours     
---
      
--- CASE    wdj.PLAN_MAINTENANCE    WHEN  'Y' THEN 'FFF' END PLHRS

---                       SUM(cdv.TRANSACTION_QUANTITY) END   Sum_Hours,
 ---               ENDIF;
--CASE LVL.MEANING WHEN 'Complete'      THEN '3' END COMPLETE,     
/*     
cdv.DEPARTMENT_CODE,