在 MS Access 中，如何在单个列中提取多个值？

Question

如何从单个列中解析多个值？ 问题是多个值被无关的（出于我的目的）数据包围。 示例：

Select * from my_table:
Fname   Lname    Data
Fred    Smith    @3aXXXX;Name:AA;@43deXXXX;Name:BB;@5433ed9;NAME:ABC;*#!XXXXXXXX;NAME:MyPetDog;@#IDXXXX

对于数据列，我想从列中提取“名称：”字段后面的所有值。这将是 "Name:" 之后和 ";" 之前的文本。在上面的例子中：

Select Fname, Lname, [DATA] from my_table

Fname   Lname    [*Parsed* DATA]
Fred    Smith    AA,BB, ABC, MyPetDog

解决上述问题将是一个巨大的帮助。但是，我真正想做的是查找/替换（SWITCH 等）从字符串返回的每个值：

Fname   Lname    [Translated DATA]
Fred    Smith    Airport, Bus Station, Restaurant, FIDO

对于使用名义数据，我深表歉意。我的实际脚本（在另一个网络上）涉及几个表连接以获取列 DATA。我只是不知道如何从这个大字符串中提取特定值（除了提取完整数据集并在之后使用 AWk 或 MS Excel 清理数据）。

感谢有关解决此问题的任何帮助或提示。

凯文 L.

Answer 1

按照@AppleCore 的建议，使用外部函数来避免混乱。

SELECT 
    Fname, 
    Lname, 
    CleanField([Data]) AS TranslatedData
FROM 
    my_table;

将函数（使用Select Case .. 进行转换）复制粘贴到一个新模块中，进入菜单Debug, Compile，然后将该模块另存为Module1_：

Public Function CleanField(ByVal Value As String) As String

    Dim Parts   As Variant
    Dim Index   As Integer
    Dim Part    As String
    Dim Text    As String
    
    Parts = Split(";" & Value, ":")
    For Index = LBound(Parts) To UBound(Parts)
        Part = Split(Parts(Index), ";")(0)
        
        Select Case Part
            Case Is = "AA"
                Part = "Airport"
            Case Is = "BB"
                Part = "Bus station"
            Case Is = "ABC"
                Part = "Restaurant"
            Case Is = "MyPetDog"
                Part = "FIDO"
        End Select
        
        If Part <> "" Then
            If Text <> "" Then
                Text = Text & ", "
            End If
            Text = Text & Part
        End If
    Next
    
    CleanField = Text

End Function

例子：

Fname   Lname   TranslatedData
------- ------- --------------------------------------
Fred    Smith   Airport, Bus station, Restaurant, FIDO
George  Olsen   Airport, Restaurant, Bus station, FIDO
Tina    Doe     Restaurant, Bus station, FIDO

Answer 2

我建议创建一个小的 VBA 函数，它获取“丑陋”数据并使用 Split 函数将其拆分出来。比如：

Public Function fSplitData(strData As String) As String
    Dim aData() As String
    Dim lngLoop1 As Long
    aData = Split(strData, ";")
    For lngLoop1 = LBound(aData) To UBound(aData)
        If Left(aData(lngLoop1), 5) = "Name:" Then
            fSplitData = fSplitData & Mid(aData(lngLoop1), 6) & ","
        End If
    Next lngLoop1
    If Right(fSplitData, 1) = "," Then fSplitData = Left(fSplitData, Len(fSplitData) - 1)
End Function

这给出了所需的输出：

AA,BB,ABC,MyPetDog

而且，您可以使用记录集从查找表中获取数据，而不仅仅是连接提取的值。在您的情况下，由于您只有 8 个值，您可以在代码中使用 If：

Public Function fSplitData(strData As String) As String
    Dim strLookup As String
    Dim aData() As String
    Dim lngLoop1 As Long
    aData = Split(strData, ";")
    For lngLoop1 = LBound(aData) To UBound(aData)
        If Left(aData(lngLoop1), 5) = "Name:" Then
            strLookup = Mid(aData(lngLoop1), 6)
            If strLookup = "AA" Then
                fSplitData = fSplitData & "Airport,"
            ElseIf strLookup = "BB" Then
                fSplitData = fSplitData & "Bus Station,"
            ElseIf strLookup = "ABC" Then
                fSplitData = fSplitData & "Restaurant,"
            ElseIf strLookup = "MyPetDog" Then
                fSplitData = fSplitData & "FIDO,"
            End If
        End If
    Next lngLoop1
    If Right(fSplitData, 1) = "," Then fSplitData = Left(fSplitData, Len(fSplitData) - 1)
End Function

然后您可以在查询中使用此函数，就像使用标准 Access 函数一样。所以你的 SQL 看起来像：

SELECT 
FName, 
LName, 
Data, 
fSplitData([Data]) AS TranslatedData
FROM Table1;

问候，

Answer 3

感谢@Applecore，我有一个几乎可以工作的解决方案（虽然可能不是最好的解决方案）：

SELECT Fname,
       Lname,
       SWITCH(data like "*AA*","Airport")&", "&
       SWITCH(data like "*BB*", "Bus Station")&", "&
       SWITCH(data like "*ABC*", "Restaurant")&", "&
       SWITCH(data like "*MyPetDog*","FIDO") as DATA

Fname   Lname    [Translated DATA]
Fred    Smith    Airport, Bus Station, Restaurant, FIDO

唯一的问题是，如果值不存在，那么我会得到额外的逗号。例如，如果 BB 是唯一存在的值，那么我得到：

Fname   Lname    [Translated DATA]
Fred    Smith    , Bus Station, ,