Question

我们将汇率存储在一个表格中，并且每周更新几次以获取最新的汇率。我正在尝试能够在销售订单上记录日期，并为其分配订单时处于活动状态的汇率。下面是汇率列表及其生效日期以及销售订单的列表示例，以及效果率应该是多少（交易率@订单时间，这是我想要的内容）。

currate.effectivedate      currate.currentrate
12/2/2012                  0.55
12/7/2012                  0.52
12/13/2012                 0.54
12/19/2012                 0.53
12/22/2012                 0.56

orderhed.orderdate        orderhed.ordernum     Exchage Rate @ date of order
12/4/2012                  105                  0.55
12/8/2012                  111                  0.52
12/9/2012                  116                  0.52
12/19/2012                 120                  0.53
12/28/2012                 123                  0.56

我有一个我一直试图做的例子，但它不起作用。首先，由于currate.evaliddate上的MAX函数，我无法想到如何引入currate.currentrate字段。然后对于t_rate.effectivedate，我只获得表周期的汇率的MAX天，而不是＆lt; = orderhed.orderdate的最大日期。我需要MAX currate.effectivedate小于或等于orderhed.orderdate，以获得在订单生效时生效的生效日期（和相应的currentrate.currentrate）。如果我重复自己，或者没有意义，我很抱歉。如果下面我的悲伤小问题不明显，我对编写查询非常新，所以我能得到的任何帮助都非常感谢。

SELECT     
orderhed.ordernum, 
orderhed.orderdate, 
orderdtl.orderline, 
orderdtl.unitprice, 
orderdtl.docunitprice, 
orderdtl.discount, 
orderdtl.docdiscount, 
t_rate.effectivedate

FROM         orderhed LEFT OUTER JOIN

(SELECT     rate1.company, MAX(rate1.effectivedate) AS effectivedate, order1.orderdate
FROM         currrate as rate1 INNER JOIN
                  orderhed AS order1 ON rate1.company = order1.company
WHERE     (rate1.company = 'lotcol') AND (rate1.currencycode = 'usd') 
GROUP BY rate1.company, order1.orderdate) 

AS t_rate ON orderhed.company = t_rate.company AND t_rate.orderdate <= orderhed.orderdate 
                        INNER JOIN
                  orderdtl ON orderhed.company = orderdtl.company 
WHERE     (orderhed.company = 'lotcol')

更新---

感谢@LastCoder，你回答的是在正确的方向上推动我。在一天结束时，这正是有效的：

SELECT     orderhed.ordernum, orderhed.orderdate, orderdtl.orderline, orderdtl.unitprice, orderdtl.docunitprice, orderdtl.discount, orderdtl.docdiscount, t_rate.effectivedate, 
                  t_rate.ordernum AS Expr1, t_rate1.currentrate
FROM         orderhed INNER JOIN
                      (SELECT     rate1.company, MAX(rate1.effectivedate) AS effectivedate, order1.orderdate, order1.ordernum
                        FROM          currrate AS rate1 INNER JOIN
                                               orderhed AS order1 ON rate1.company = order1.company AND rate1.effectivedate <= order1.orderdate
                        WHERE      (rate1.company = 'lotcol') AND (rate1.currencycode = 'usd')
                        GROUP BY rate1.company, order1.orderdate, order1.ordernum) AS t_rate ON orderhed.ordernum = t_rate.ordernum AND orderhed.company = t_rate.company AND 
                  t_rate.orderdate <= orderhed.orderdate INNER JOIN
                      (SELECT     company, currencycode, effectivedate, currentrate
                        FROM          currrate AS currrate_1
                        WHERE      (company = 'lotcol') AND (currencycode = 'usd')) AS t_rate1 ON t_rate.company = t_rate1.company AND 
                  t_rate.effectivedate = t_rate1.effectivedate INNER JOIN
                  orderdtl ON orderhed.company = orderdtl.company AND orderhed.ordernum = orderdtl.ordernum
WHERE     (orderhed.company = 'lotcol')
ORDER BY orderhed.ordernum

Answer 1

SELECT o.orderdate
    , ISNULL(r.effectivedate, (
        SELECT MAX(effectivedate) FROM t_rate WHERE effectivedate < o.orderdate
    )
FROM orderhed o
LEFT JOIN t_rate r ON o.orderdate = r.effectivedate

您的问题有一个最小的解决方案。您需要将“orderdate”与等于或最接近它的“effectivedate”匹配。

另一个表中的MAX Date＆lt; = to date

1 个答案: