Question

我有一个如下所示的汇率表

FromCurrency    ToCurrency          ValidFrom               ExchangeRate
USD             ZAR         2012-01-05 00:00:00.000         7.7260000000
USD             ZAR         2012-01-04 00:00:00.000         7.6740000000
USD             ZAR         2012-01-03 00:00:00.000         7.4601000000
USD             ZAR         2012-01-02 00:00:00.000         7.7600000000
USD             ZAR         2012-01-01 00:00:00.000         8.0945000000
EUR             NOK         2012-01-05 00:00:00.000         7.5881000000
EUR             NOK         2012-01-04 00:00:00.000         7.5974000000
EUR             NOK         2012-01-03 00:00:00.000         7.4494000000
EUR             NOK         2012-01-02 00:00:00.000         7.6606000000
EUR             NOK         2012-01-01 00:00:00.000         7.7740000000
USD             AED         2012-01-05 00:00:00.000         3.6731000000
USD             AED         2012-01-04 00:00:00.000         3.6731000000

我的主要表是

Transaction Date    Amount  Currency    FromCurrency
13971   5/27/2011    8000     USD   USD
13971   7/31/2011   -6809.4   ZAR   USD
13971   8/30/2011   -425.59   ZAR   USD
13971   9/27/2011   -6809.4   ZAR   USD
67467   11/8/2011    5000     GBP   GBP
67467   12/21/2011  -5195.06  ZAR   GBP
67467   1/30/2012   -5195.06  ZAR   GBP
81181   4/15/2011    6000     USD   USD
81181   6/28/2011   -5159.03  ZAR   USD
82418   10/21/2011   5000     EUR   EUR
82418   1/27/2012   -3919.97  NOK   EUR

以上是表的示例数据，我的实际表有数百万条记录。我必须将金额乘以汇率栏（来自汇率表），并将相应的FromCurrency（来自汇率表）更新为我表格中的货币栏。

我尝试了很多方法但找不到解决方法。这里棘手的部分是我的表在汇率表中没有匹配的日期。

汇率应该像这样应用。如果我的交易日期是2012年2月20日，货币是ZAR而且FromCurrency是USD，那么我必须从汇率表中选择以下行

USD             ZAR         2012-01-02 00:00:00.000         7.7600000000

Answer 1

update transactions
set FromCurrencyAmount = transactions.amount * 
    (select top 1 exchangerate from exchangerates where validfrom <= transactions.date 
       and transactions.fromcurrency = exchangerates.fromcurrency
       and transactions.currency = exchangerates.tocurrency
       order by validfrom desc)

选择

select transactions.*, 
    (select top 1 exchangerate from exchangerates where validfrom <= transactions.date 
       and transactions.fromcurrency = exchangerates.fromcurrency
       and transactions.currency = exchangerates.tocurrency
       order by validfrom desc) 
from transactions

Answer 2

另一种选择是：

select * from
transact t1 join exchRate e1 on t1.FromCurrency = e1.FromCurrency 
and t1.ToCurrency = e1.ToCurrency
and t1.tdate > e1.ValidFrom 
and not exists 
(select 1 from exchRate where ValidFrom < t1.tdate and ValidFrom > e1.ValidFrom)

Answer 3

我希望明白

 SELECT T3.*,
   T4.DATEMAX,
   T4.VALUESELECTED
   FROM   TRANSACTIONS AS T3
   INNER JOIN
   (SELECT T.CURRENCY,
           T.FROMCURRENCY,
           T.DATEMAX,
           T2.EXCHANGERATE AS VALUESELECTED
    FROM   (SELECT   CURRENCY,
                     FROMCURRENCY,
                     MAX(ValidFrom) AS DATEMAX
            FROM     ExChangeRate
            WHERE    ValidFrom <= T3.DATE
            GROUP BY Currency, FromCurrency) AS T
           INNER JOIN
           ExChangeRate AS T2
           ON T.CURRENCY = T2.CURRENCY
              AND T.FROMCURRENCY = T2.FROMCURRENCY
              AND T.DATEMAX = T2.VALIDFROM) AS T4
   ON T4.CURRENCY = T3.CURRENCY
      AND T4.FROMCURRENCY = T3.FROMCURRENCY;

通过加入更新表

3 个答案: