问sql有关问题

问sql问题
select rownum rowindex,
        count(*) js,
       a.cpid,
       a.hssl,
       TO_CHAR(a.dj, 'FM99999999990.00') dj,
       (sum(nvl(a.sl, 0)) || ' ' || a.jldw) sljl,
       TO_CHAR(sum(a.je), 'FM99999999990.00') zh,
       (a.product || '  ' || TO_CHAR(a.hssl, 'FM99999999990.00') || ' ' ||a.HSDW) product, 
       a.bz,
       a.je
  from (SELECT count(*) js,
               a.sfdjid,
               a.cpid,
               b.CPBM,
               b.PRODUCT,
               
               b.JLDW,
               1,
               b.HSDW,
               a.sl,
               a.hssl,
               a.dj,
               (a.sl * a.dj * count(*)) je,
               a.bz
              
               
          FROM kc_sfdjmx a
          JOIN vw_kc_dm_dmsx b
            ON a.cpid = b.CPID
         WHERE a.sfdjid = '" + sfdjid + "'
         group by a.cpid,
                  a.sfdjid,
                  a.cpid,
                  b.CPBM,
                  b.PRODUCT,
                  b.bjfs,
                  b.JLDW,
                  b.HSDW,
                  a.hssl,
                  a.sl,
                  a.dj,
                  a.je,
                  a.bz
                  ) a
group by a.cpid, a.dj, a.product, a.jldw, a.hssl, a.hsdw,a.BZ,a.je
报错：不是group by 表达式
我在group by加了个 rowindex 还是错误的"rowindex" 标示符无效。
是不是rownum不能和group by一起用呢
------解决方案--------------------

引用:

select rownum rowindex,
        count(*) js,
       a.cpid,
       a.hssl,
       TO_CHAR(a.dj, 'FM99999999990.00') dj,
       (sum(nvl(a.sl, 0)) 
------解决方案--------------------
 ' ' 
------解决方案--------------------
 a.jldw) sljl,
       TO_CHAR(sum(a.je), 'FM99999999990.00') zh,
       (a.product 
------解决方案--------------------
 '  ' 
------解决方案--------------------
 TO_CHAR(a.hssl, 'FM99999999990.00') 
------解决方案--------------------
 ' ' 
------解决方案--------------------
a.HSDW) product, 
       a.bz,