【问题标题】：Use SQL to display count of min and count of max within group使用 SQL 显示组内的最小计数和最大计数
【发布时间】：2016-02-23 19:56:15
【问题描述】：

目标

我正在寻找一种方法来计算等于组的最小值或最大值的项目数。我有每隔几天收到的物品，每两周输入一次。我需要查看每个 EntryDate 的 Min 和 Max ReceivedDate，以及 Min 和 Max 的项目计数。在 MS Access 中使用 SQL。

输入

tblItem

|    EntryDate    |   ReceivedDate   |
--------------------------------------
|   01/01/2016    |    16/12/2015    |
|   01/01/2016    |    15/12/2015    |
|   01/01/2016    |    10/12/2015    |
|   01/01/2016    |    10/12/2015    |
|   01/01/2016    |    10/12/2015    |
|   01/01/2016    |    10/12/2015    |
|   15/01/2016    |    05/01/2016    |
|   15/01/2016    |    05/01/2016    |
|   15/01/2016    |    04/01/2016    |
|   15/01/2016    |    03/01/2016    |
|   15/01/2016    |    03/01/2016    |
|   15/01/2016    |    03/01/2016    |

当前查询

SELECT tblItem.EntryDate, 
Min(tblItem.ReceivedDate) AS MinReceivedDate, 
Max(tblItem.ReceivedDate) AS MaxReceivedDate
FROM tblItem
GROUP BY tblItem.EntryDate;

电流输出

Query1

| EntryDate  | MinReceivedDate | MaxReceivedDate |
--------------------------------------------------
| 01/01/2016 |    10/12/2015   |   16/12/2015    |
| 15/01/2016 |    03/01/2016   |   05/01/2016    |

期望的输出

Query1

| EntryDate  | MinReceivedDate | CountOfMin | MaxReceivedDate | CountOfMax |
---------------------------------------------------------------------------
| 01/01/2016 |    10/12/2015   |      4     |   16/12/2015    |      1     |
| 15/01/2016 |    03/01/2016   |      3     |   05/01/2016    |      2     |

【问题讨论】：

标签： sql ms-access correlated-subquery

【解决方案1】：

我不知道 MS Access 是否允许这样的子查询。如果这不起作用，请告诉我，我将删除答案。否则：

SELECT
    SQ.EntryDate,
    SQ.MinReceivedDate,
    SUM(IIF(I.ReceivedDate = SQ.MinReceivedDate, 1, 0)) AS CountOfMin,
    SQ.MaxReceivedDate,
    SUM(IIF(I.ReceivedDate = SQ.MaxReceivedDate, 1, 0)) AS CountOfMax
FROM (
    SELECT
        SQI.EntryDate,
        MIN(SQI.ReceivedDate) AS MinReceivedDate,
        MAX(SQI.ReceivedDate) AS MaxReceivedDate
    FROM
        tblItem SQI
    GROUP BY
        SQI.EntryDate
    ) SQ
INNER JOIN tblItem I ON I.EntryDate = SQ.EntryDate
GROUP BY
    SQ.EntryDate,
    SQ.MinReceivedDate,
    SQ.MaxReceivedDate

【讨论】：

我收到以下错误消息：查询表达式中的语法错误（缺少运算符）'SUM(CASE WHEN I.DateReceived = SQ.MinReceivedDate THEN 1 ELSE 0 End)'。
Access 好像不支持CASE 语句，但我找到了正确的函数。我现在会更新。