Question

这是指我之前的帖子：Link

系统：Sql Server 2012

使用此脚本，如果CutoffDate的日期是星期六或星期日，我会采用星期五值。

SELECT DISTINCT dbo.ECB.Currency + '-' + CAST(dbo.myTable.CutoffDate AS varchar(30)) AS ComboCurrDate, dbo.ECB.Rate AS ECBrate
FROM         dbo.ECB INNER JOIN
                      dbo.myTable ON dbo.ECB.Date = CASE WHEN datepart(weekday, dbo.myTable.CutoffDate) IN (6, 7) THEN dateadd(d, - ((datepart(weekday, 
                      dbo.myTable.CutoffDate) + 1 + @@DATEFIRST) % 7), dbo.myTable.CutoffDate) ELSE dbo.myTable.CutoffDate END AND 
                      dbo.ECB.Currency = dbo.myTable.InvoiceCurrency
WHERE     (dbo.myTable.InvoiceCurrency NOT LIKE 'EUR%')

但现在我需要重写这个以处理假期。或者更好的是，处理ECB表中的不存在的记录。

例如：3月29日星期五，ECB表中没有记录，但myTable.CutoffDate设置为此日期。有了上面的脚本，我今天没有得到价值。

我现在如何将第28个的ECB值分配给CutoffDate？

一般情况下：如果ECB表中没有一天的记录，那么请尝试ECB表中的上一个日期，依此类推。

希望我能清楚地解释清楚。

感谢您的帮助。

Answer 1

我认为您应该获取数据中每个截止日期的最新ECB日期。

以下是相关子查询：

SELECT DISTINCT ECB.Currency + '-' + CAST(m.CutoffDate AS varchar(30)) AS ComboCurrDate,
                ECB.Rate AS ECBrate
FROM (select m.*,
             (select     top     1     ecb.date
              from ecb
               where ecb.currency = m.InvoiceCurrency and ecb.date <= m.CutoffDate
               order by ecb.date desc
             ) as ECBDateToUse
      from mytable
     ) m left outer join
     ECB 
     ON ECB.Date = m.ECBDateToUse and
        ECB.Currency = m.InvoiceCurrency
WHERE (m.InvoiceCurrency NOT LIKE 'EUR%')

Answer 2

我认为您正在寻找LEFT OUTER JOIN

SELECT DISTINCT dbo.ECB.Currency + '-' + CAST(dbo.myTable.CutoffDate AS varchar(30)) AS ComboCurrDate, dbo.ECB.Rate AS ECBrate
FROM mytable LEFT OUTER JOIN ECB ON dbo.ECB.Date = CASE WHEN datepart(weekday, dbo.myTable.CutoffDate) IN (6, 7) THEN dateadd(d, - ((datepart(weekday, 
                  dbo.myTable.CutoffDate) + 1 + @@DATEFIRST) % 7), dbo.myTable.CutoffDate) ELSE dbo.myTable.CutoffDate END AND 
                  dbo.ECB.Currency = dbo.myTable.InvoiceCurrency

无论ECB表中是否有结果，都会从mytable返回所有记录。您可以添加AND ECB.date IS NULL的过滤器，以仅提取ECB表中不存在的记录

Answer 3

使用外连接，并将所有影响连接外侧的谓词条件置于连接条件中，而不是在where子句中。另外，我可以谦虚地建议你使用表别名和格式来使sql更具可读性。如果读者能够轻松理解您的查询，您将更快地得到问题的答案。

SELECT DISTINCT e.Currency + '-' + 
    CAST(m.CutoffDate AS varchar(30)) ComboCurrDate, 
    e.Rate ECBrate
FROM dbo.ECB e  Left JOIN dbo.myTable m 
     ON e.Currency = m.InvoiceCurrency
          And m.InvoiceCurrency NOT LIKE 'EUR%'
          And e.Date = 
               CASE WHEN datepart(weekday, m.CutoffDate) IN (6, 7) 
                    THEN dateadd(d, - ((datepart(weekday, 
                         m.CutoffDate) + 1 + @@DATEFIRST) % 7), m.CutoffDate) 
                    ELSE m.CutoffDate END

如果日期是假日或周末，则SQL替换日期值

3 个答案: