如何从此SELECT中排除重复项？

Question

这是发票历史记录表中的数据。

invoicehistoryID WorkOrderNumber InvoiceDate

1                1               2017-06-13 12:00:49
2                1               2017-06-13 12:05:05
3                10              2017-06-14 12:32:59
4                10              2017-06-14 14:26:25
5                1               2017-06-14 14:26:54
6                1               2017-06-22 10:12:49

我需要什么SELECT查询来获取每个WorkOrderNumber的最新InvoiceDate（由WorkOrderNumber排序）？ 换句话说，我怎么能得到这个：

invoicehistoryID WorkOrderNumber InvoiceDate
6                1               2017-06-22 10:12:49
4                10              2017-06-14 14:26:25

我在DISTINCT上还没有成功。 LIMIT尚未成功，因为我的发票历史记录表将会增长。

这几乎可行，

SELECT max(InvoiceDate),WorkOrderNumber FROM `invoicehistory` GROUP BY WorkOrderNumber

但没有得到invoicehistoryID。
这个

SELECT max(InvoiceDate),WorkOrderNumber, invoicehistoryID FROM `invoicehistory` GROUP BY WorkOrderNumber, invoicehistoryID

返回所有行。

Answer 1

尝试：

SELECT invoicehistoryID, WorkOrderNumber, InvoiceDate
FROM (SELECT invoicehistoryID, WorkOrderNumber, InvoiceDate
  FROM TABLE
  ORDER BY WorkOrderNumber ASC, InvoiceDate DESC
) inv
GROUP BY WorkOrderNumber

Answer 2

• 集合D：是每个工单的最大发票日期。
• 设置IH是整个发票历史记录。

通过在日期和订单数字上将D加入IH，我们可以获取缺少的invoicehistoryID和其他信息（如果需要）。

SELECT IH.invoiceHistoryID, IH.WorkOrderNumber, IH.InvoiceDate
FROM InvoiceHistory IH
INNER JOIN (SELECT max(invoiceDate) mInvoiceDate, WorkOrderNumber
            FROM invoicehistory
            GROUP BY workorderNumber) D
 on D.mInvoiceDate = IH.InvoiceDate
and D.WorkOrderNumber = IH.workOrderNumber

如果mySQL支持，交叉应用将是实现此目标的另一种方法

或使用窗口函数分配行号并将结果限制为最新日期（如果mySQL支持）。

Answer 3

在ms sql中得到答案之前，我没有注意到mySql：

 CREATE TABLE #tmp(
    InvoiceHistoryID  INT,
    WorkOrderNumber INT,
    InvoiceDate datetime
    )

   INSERT INTO #tmp VALUES(1,1,'2017-06-13 12:00:49')
   INSERT INTO #tmp VALUES(2,1,'2017-06-13 12:05:05')
   INSERT INTO #tmp VALUES(3,10,'2017-06-14 12:32:59')
   INSERT INTO #tmp VALUES(4,10,'2017-06-14 12:32:59')
   INSERT INTO #tmp VALUES(5,1,'2017-06-14 14:26:54')
   INSERT INTO #tmp VALUES(6,1,'2017-06-22 10:12:49')


    SELECT 
       t.InvoiceHistoryID,
       t.WorkOrderNumber,
       m.InvoiceDate
    FROM #tmp t JOIN (SELECT MAX(InvoiceHistoryID) AS  InvoiceHistoryID, 
                             MAX(InvoiceDate) AS InvoiceDate
                    FROM #tmp 
                    GROUP BY WorkOrderNumber ) AS m 
    ON t.InvoiceHistoryID = m.InvoiceHistoryID                  

    DROP TABLE #tmp