oracle 分组 聚合数据 单字段聚合问题

SELECT
-- max 加这个只是为了让字段不在分组里写
	max(id) id,
	max(stockorg_name) stockorg_name,
	max(vbillcode) vbillcode,
	max(source_no) source_no,
-- newvbillcode 这个字段做分组条件
	newvbillcode,
	max(dbilldate) dbilldate,
	max(billtypename) billtypename,
	max(vtrantypecode) vtrantypecode,
	max(stordoc_code) stordoc_code,
	max(stordoc_name) stordoc_name,
	max(crowno) crowno,
	max(MATERIAL_code) MATERIAL_code,
	max(MATERIAL_name) MATERIAL_name,
	max(vbatchcode) vbatchcode,
	to_char ( sum( nnum ) ) AS nnum,
	to_char ( sum( nassistnum ) ) AS nassistnum 
FROM
	(
SELECT
	to_char ( rownum ) AS id,
	NCC10.org_stockorg.NAME AS stockorg_name,
	NCC10.IC_FINPRODIN_H.vbillcode,
	NCC10.IC_FINPRODIN_H.VDEF44 AS source_no,
CASE
	
	WHEN instr( NCC10.IC_FINPRODIN_H.vbillcode, '-',- 1 ) > 0 THEN
	substr( NCC10.IC_FINPRODIN_H.vbillcode, 1, instr( NCC10.IC_FINPRODIN_H.vbillcode, '-',- 1 ) - 1 ) ELSE NCC10.IC_FINPRODIN_H.vbillcode 
	END newvbillcode,
	substr( NCC10.IC_FINPRODIN_H.dbilldate, 1, 10 ) AS dbilldate,
	NCC10.bd_billtype.billtypename,
	NCC10.IC_FINPRODIN_H.vtrantypecode,
	NCC10.bd_stordoc.CODE AS stordoc_code,
	NCC10.bd_stordoc.NAME AS stordoc_name,
	NCC10.IC_FINPRODIN_B.crowno,
	NCC10.BD_MATERIAL.CODE AS MATERIAL_code,
	NCC10.BD_MATERIAL.NAME AS MATERIAL_name,
	NCC10.IC_FINPRODIN_B.vbatchcode,
	NCC10.IC_FINPRODIN_B.nnum,
	NCC10.IC_FINPRODIN_B.nassistnum 
FROM
	NCC10.IC_FINPRODIN_H
	LEFT JOIN NCC10.IC_FINPRODIN_B ON NCC10.IC_FINPRODIN_H.cgeneralhid = NCC10.IC_FINPRODIN_B.cgeneralhid
	LEFT JOIN NCC10.BD_MATERIAL ON NCC10.IC_FINPRODIN_B.cmaterialoid = NCC10.BD_MATERIAL.pk_material 
	AND NCC10.BD_MATERIAL.DR = 0
	LEFT JOIN NCC10.bd_measdoc ON NCC10.bd_measdoc.pk_measdoc = NCC10.IC_FINPRODIN_B.castunitid 
	AND NCC10.bd_measdoc.DR = 0
	LEFT JOIN NCC10.org_stockorg ON NCC10.org_stockorg.pk_stockorg = NCC10.IC_FINPRODIN_H.pk_org 
	AND NCC10.org_stockorg.DR = 0
	LEFT JOIN NCC10.bd_stordoc ON NCC10.bd_stordoc.pk_stordoc = NCC10.IC_FINPRODIN_H.cwarehouseid 
	AND NCC10.bd_stordoc.DR = 0
	LEFT JOIN NCC10.bd_billtype ON NCC10.bd_billtype.pk_billtypecode = NCC10.IC_FINPRODIN_H.vtrantypecode 
	AND NCC10.bd_billtype.DR = 0 
WHERE
	NCC10.IC_FINPRODIN_H.DR = 0 
	AND NCC10.IC_FINPRODIN_B.DR = 0 
	AND NCC10.IC_FINPRODIN_H.dbilldate >= concat( to_char ( add_months ( last_day( sysdate ) + 1,- 2 ), 'yyyy-MM-dd' ), ' 00:00:00' ) 
	AND NCC10.IC_FINPRODIN_H.dbilldate < concat( to_char ( add_months ( last_day( sysdate ) + 1,- 1 ), 'yyyy-MM-dd' ), ' 00:00:00' ) 
	)  b
GROUP BY
	newvbillcode