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')

人數和金額一樣

當是以下就不一樣了

 
SELECT COUNT (distinct b.f_username) num, SUM (b.f_paymoney) allmoney
  FROM t_base_succprouser b
 WHERE b.f_lotid IN (1, 15, 17, 10000)
   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 (1, 15, 17, 10000)
                         )
   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')

和

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  (1, 15, 17, 10000)
And bs.f_lotid IN (1, 15, 17, 10000)
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

人數一樣，金額差別很多！統計的表一樣，時間條件一樣，ID也一樣，上面語句產生同樣的結構，為什麼多增加幾個ID就不一樣呢？

為什麼呢？因為根據f_username 連線 

 USERNAME    ID    MONEY    USERNAME    ID    MONEY
1    a    17    700    a    1    200
2    a    15    600    a    1    200
3    a    1    500    a    1    200
4    a    17    700    a    15    300
5    a    15    600    a    15    300
6    a    1    500    a    15    300
7    a    17    700    a    17    400
8    a    15    600    a    17    400
9    a    1    500    a    17    400
10    b    15    200    b    1    400
11    b    1    100    b    1    400
12    b    15    200    b    15    400
13    b    1    100    b    15    400

最後改成

Select  
   bu.f_Comechannel,Count(Distinct bs.f_username) x ,Sum(bs.f_Paymoney) pmoney
From t_Base_Succprouser bs
Inner Join t_Base_Userinfo bu On   bu.f_Username = bs.f_username
 
Where bs.f_lotid IN (1, 15, 17, 10000)
And bs.f_Expectenddate Between to_date('2009-01-01','yyyy-mm-dd') And to_date('2009-09-26','yyyy-mm-dd')
And bs.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 (1, 15, 17, 10000)
                         )
Group By bu.f_Comechannel