sql - MS Access SQL， "function calls"

Question

我正在涉足 SQL，现在使用 Access，因为我厌倦了尝试在 Excel 中编写条件查询，并且我有一个 SQL 查询，除了列名之外都有重复，非常像函数，我想通过执行 CountSubCategories(Category) 之类的操作来清理多余的内容，以减少冗余代码，如下所示...

SELECT
COUNT(*) AS “Support_Interactions”,
SUM(IIF([Type of Inquiry] = "Confidence Check",1, 0)) AS ConfidenceCheck,
   SUM(IIF(([Type of Inquiry] = "Confidence Check") AND 
   ([Billing]<>NULL),1, 0)) AS CC_Sub_Billing,
   SUM(IIF(([Type of Inquiry] = "Confidence Check") AND 
   ([General & CBS]<>NULL),1, 0)) AS CC_Sub_General&CBS,
   SUM(IIF(([Type of Inquiry] = "Confidence Check") AND 
   ([Phone]<>NULL),1, 0)) AS CC_Sub_Phone,
   SUM(IIF(([Type of Inquiry] = "Confidence Check") AND 
   ([Process]<>NULL),1, 0)) AS CC_Sub_Process,
   SUM(IIF(([Type of Inquiry] = "Confidence Check") AND 
   ([Tools]<>NULL),1, 0)) AS CC_Sub_Tools,
   SUM(IIF(([Type of Inquiry] = "Confidence Check") AND 
   ([Technical Support]<>NULL),1, 0)) AS CC_Sub_TechnicalSupport,
   SUM(IIF(([Type of Inquiry] = "Confidence Check") AND 
   ([WO/SC]<>NULL),1, 0)) AS CC_Sub_WO&SC,
SUM(IIF([Type of Inquiry] = "Product Knowledge",1, 0)) AS ProductKnowledge,
   SUM(IIF(([Type of Inquiry] = " Product Knowledge ") AND 
   ([Billing]<>NULL),1, 0)) AS CC_Sub_Billing,
   SUM(IIF(([Type of Inquiry] = " Product Knowledge ") AND 
   ([General & CBS]<>NULL),1, 0)) AS CC_Sub_General&CBS,
   SUM(IIF(([Type of Inquiry] = " Product Knowledge ") AND 
   ([Phone]<>NULL),1, 0)) AS CC_Sub_Phone,
   SUM(IIF(([Type of Inquiry] = " Product Knowledge ") AND 
   ([Process]<>NULL),1, 0)) AS CC_Sub_Process,
   SUM(IIF(([Type of Inquiry] = " Product Knowledge ") AND 
   ([Tools]<>NULL),1, 0)) AS CC_Sub_Tools,
   SUM(IIF(([Type of Inquiry] = " Product Knowledge ") AND 
   ([Technical Support]<>NULL),1, 0)) AS CC_Sub_TechnicalSupport,
   SUM(IIF(([Type of Inquiry] = " Product Knowledge ") AND 
   ([WO/SC]<>NULL),1, 0)) AS CC_Sub_WO&SC,

正如您所看到的，父类别存在相同的子类别，那么我如何能够预先定义一个函数并使用类别作为变量来调用它？

非常感谢!

Answer 1

MS access SQL 不允许这样做，但 VBA 可以。

您基本上应该在类别和子类别上使用 2 个嵌套循环来构建 SQL 字符串

我使用集合来处理猫和子猫:

Sub StackOverflow_Solution()

    Dim colCat As New Collection
    Dim colSub  As New Collection
    Dim varCat As Variant
    Dim varSub As Variant
    Dim strSQL As String
    Dim RST As Recordset

    ' fill in categories
    colCat.Add "Confidence Check"
    colCat.Add "Product Knowledge"

    ' fill in sub categories
    colSub.Add "Billing"
    colSub.Add "General "
    colSub.Add "Phone"
    colSub.Add "Process"
    colSub.Add "Tools"


    ' initiate SQL query
    strSQL = "SELECT " & vbCrLf & _
             "COUNT(*) AS 'Support_Interactions', " & vbCrLf

    ' Looping on all categories
    For Each varCat In colCat

        ' Adding category count
        strSQL = strSQL & "SUM(IIF([Type of Inquiry] = '" & varCat & "',1, 0)) AS " & Replace(varCat, " ", "") & ", " & vbCrLf

        ' Looping on all sub categories
        For Each varSub In colSub

            strSQL = strSQL & "    SUM(IIF(([Type of Inquiry] = '" & varCat & "') AND " & vbCrLf & _
                              "    ([" & varSub & "]<>NULL),1, 0)) AS CC_Sub_" & Replace(varSub, " ", "") & ", " & vbCrLf
        Next

    Next

    Debug.Print strSQL


    ' Trigger query
    Set RST = CurrentDb.OpenRecordset(strSQL)

    If Not RST.BOF Then

        'reading resulting recordset

        While Not RST.EOF

            'dostuff with your data

            RST.MoveNext

        Wend

    End If

End Sub

有了这个子程序，您的 strSQL 将包含以下内容:

SELECT 
COUNT(*) AS 'Support_Interactions', 
SUM(IIF([Type of Inquiry] = 'Confidence Check',1, 0)) AS ConfidenceCheck, 
    SUM(IIF(([Type of Inquiry] = 'Confidence Check') AND 
    ([Billing]<>NULL),1, 0)) AS CC_Sub_Billing, 
    SUM(IIF(([Type of Inquiry] = 'Confidence Check') AND 
    ([General ]<>NULL),1, 0)) AS CC_Sub_General, 
    SUM(IIF(([Type of Inquiry] = 'Confidence Check') AND 
    ([Phone]<>NULL),1, 0)) AS CC_Sub_Phone, 
    SUM(IIF(([Type of Inquiry] = 'Confidence Check') AND 
    ([Process]<>NULL),1, 0)) AS CC_Sub_Process, 
    SUM(IIF(([Type of Inquiry] = 'Confidence Check') AND 
    ([Tools]<>NULL),1, 0)) AS CC_Sub_Tools, 
SUM(IIF([Type of Inquiry] = 'Product Knowledge',1, 0)) AS ProductKnowledge, 
    SUM(IIF(([Type of Inquiry] = 'Product Knowledge') AND 
    ([Billing]<>NULL),1, 0)) AS CC_Sub_Billing, 
    SUM(IIF(([Type of Inquiry] = 'Product Knowledge') AND 
    ([General ]<>NULL),1, 0)) AS CC_Sub_General, 
    SUM(IIF(([Type of Inquiry] = 'Product Knowledge') AND 
    ([Phone]<>NULL),1, 0)) AS CC_Sub_Phone, 
    SUM(IIF(([Type of Inquiry] = 'Product Knowledge') AND 
    ([Process]<>NULL),1, 0)) AS CC_Sub_Process, 
    SUM(IIF(([Type of Inquiry] = 'Product Knowledge') AND 
    ([Tools]<>NULL),1, 0)) AS CC_Sub_Tools, 

您应该对列 WO/SC 进行一些调整，在列的别名中，您应该将“/”替换为“&”，而不是空无一物的空格。

我完成了 90% 的工作，剩下的你可以做