oracle inner join 隐藏的多次连接

Select bu.f_Comechannel,Count(Distinct x.f_username) x ,Sum(bs.f_Paymoney) pmoney
from T_BASE_USER_FIRST_TRADE_LOTTY x
Inner Join t_Base_Userinfo bu On   bu.f_Username = x.f_username
Inner Join t_Base_Succprouser bs On bs.f_Username = x.f_username
Where x.f_lotid IN (9)
And bs.f_lotid IN (9)
And x.f_tradetime Between to_date('2009-01-01','yyyy-mm-dd') And to_date('2009-09-26','yyyy-mm-dd')
And bs.f_Expectenddate Between to_date('2009-01-01','yyyy-mm-dd') And to_date('2009-09-26','yyyy-mm-dd')
Group By bu.f_Comechannel
和
SELECT COUNT (distinct b.f_username) num, SUM (b.f_paymoney) allmoney
  from t_base_succprouser b
 WHERE b.f_lotid IN (9)
   AND b.f_username IN
     (
          SELECT c.f_username
            from t_base_user_first_trade_lotty c
           WHERE c.f_tradetime BETWEEN TO_DATE ('2009/01/01-00:00:00', 'YYYY/MM/DD-HH24:MI:SS')
                                       AND TO_DATE ('2009/09/26-00:00:00','YYYY/MM/DD-HH24:MI:SS' )
             AND c.f_lotid IN (9)
                         )
   AND b.f_expectenddate BETWEEN TO_DATE ('2009/01/01-00:00:00''YYYY/MM/DD-HH24:MI:SS' )
                             AND TO_DATE ('2009/09/26-00:00:00', 'YYYY/MM/DD-HH24:MI:SS')
人数和金额一样
当是以下就不一样了
 
SELECT COUNT (distinct b.f_username) num,