Question

所以我的表格格式如下：

Project | type1 | type2 | type3 | type4  
a | 0 | 1 | 1 | 2  
b | 1 | 0 | 1 | 1  
c | 0 | 0 | 0 | 0

我需要每行的最大值，如下所示：

Project | max  
a | 2  
b | 1  
c | 0

我无法在访问中使用switch（）函数，因为我有太多的变量而且它给出了“太复杂”的错误。有任何想法吗？

SELECT Switch(
[MaxOfBudget Trigger] = 2, "Critical",
[MaxOfSchedule Trigger] = 2, "Critical",
[MaxOfSubmittals Trigger] = 2, "Critical",
[MaxOfSafety Trigger] = 2, "Critical",
[MaxOfChange Orders Trigger] = 2, "Critical",
[MaxOfContingency Trigger] = 2, "Critical",
[MaxOfRFIs Trigger] = 2, "Critical",
[MaxOfBudget Trigger] = 1, "At Risk",
[MaxOfSchedule Trigger] = 1, "At Risk",
[MaxOfSubmittals Trigger] = 1, "At Risk",
[MaxOfSafety Trigger] = 1, "At Risk",
[MaxOfChange Orders Trigger] = 1, "At Risk",
[MaxOfContingency Trigger] = 1, "At Risk",
[MaxOfRFIs Trigger] = 1, "At Risk",
[MaxOfBudget Trigger] = 0, "Okay",
[MaxOfSchedule Trigger] = 0, "Okay",
[MaxOfSubmittals Trigger] = 0, "Okay",
[MaxOfSafety Trigger] = 0, "Okay",
[MaxOfChange Orders Trigger] = 0, "Okay",
[MaxOfContingency Trigger] = 0, "Okay",
[MaxOfRFIs Trigger] = 0, "Okay", )
AS test, [Project Triggers].[Project Number]
FROM [Project Triggers];

Answer 1

您的数据库没有按照应有的方式进行标准化。您应该有一个type表，其中包含值1,2,3,4，然后是project表的连接表。

|project | type_id | value |
+--------+---------+-------+
|a       | 1       | 0     |
|a       | 2       | 1     |
|a       | 3       | 1     |
|a       | 4       | 2     |
|b       | 1       | 1     |
|b       | 2       | 0     |
|b       | 3       | 1     |
|b       | 4       | 1     |
|c       | 1       | 0     |
|c       | 2       | 0     |
|c       | 3       | 0     |
|c       | 4       | 0     |

然后，您可以执行SELECT project, max(value) FROM project_type_values GROUP BY project;之类的操作来获得结果。

Answer 2

我完全同意Daniël的回答，我希望您能够修改数据模型。但是如果你不能，你可以声明一个可以返回最大数字列表的函数：

Function MaxOfList(ParamArray varValues()) As Variant
    Dim i As Integer        'Loop controller.
    Dim varMax As Variant   'Largest value found so far.

    varMax = Null           'Initialize to null

    For i = LBound(varValues) To UBound(varValues)
      If varMax >= varValues(i) Then
        'do nothing
      Else
        varMax = varValues(i)
      End If
    Next

    MaxOfList = varMax
End Function

稍高级版本以及Min版本可以在Allen Browne's Access Tips: MinOfList() and MaxOfList() functions

找到

使用microsoft access sql选择行中的最高值

2 个答案: