Question

我的问题类似于此问题SQL Group By Having Where Statements，唯一的区别是我需要在指定日期生成所有ProductIds的最新数量，例如 ProductId 1 on 15-Feb-12 is 100＆amp;的数量ProductId 2 on 15-Feb-12 is 200，ProductId 1 on 15-Mar-12 is 150的数量＆amp; ProductId 2 on 15-Mar-12 is 250。从MS Access表跟踪月末的产品数量，如下所示。

ProductId | ReportingDate | Quantity|  
1         | 31-Jan-12     | 100     |  
2         | 31-Jan-12     | 200     |  
1         | 28-Feb-12     | 150     |  
2         | 28-Feb-12     | 250     |  
1         | 31-Mar-12     | 180     |  
2         | 31-Mar-12     | 280     |

2012年3月15日上我想要的输出应该是如下查询：

ProductId | ReportingDate | Quantity|  
1         | 28-Feb-12     | 150     |  
2         | 28-Feb-12     | 250     |

我当前的SQL语句只返回一个ProductID的结果。任何人都可以帮我扩展查询以显示所有ProductIds吗？

SELECT TOP 1 Sheet1.ProductId, Sheet1.ReportingDate AS MaxOfReportingDate, Sheet1.Quantity
FROM Sheet1
WHERE (Sheet1.ProductId = 1)
AND (Sheet1.ReportingDate < #2012/03/15#)
ORDER BY Sheet1.ReportingDate DESC

Answer 1

您需要加入一个子查询，该子查询列出了所需日期之前的最新日期：

SELECT
Sheet1.ProductId, Sheet1.ReportingDate, Sheet1.Quantity
FROM Sheet1 INNER JOIN
(SELECT Sheet1.ProductId, MAX(Sheet1.ReportingDate) AS MaxOfReportingDate
FROM Sheet1
WHERE ReportingDate < #2012/03/15#
GROUP BY ProductId) AS a 
ON Sheet1.ProductId = a.ProductId AND Sheet1.ReportingDate = a.MaxOfReportingDate
ORDER BY Sheet1.ReportingDate DESC

SQL Group By语句，分组数据的最大值

1 个答案: