在 Access 中解析字符串值

Question

我正在将 sql 导入到我的 Access 数据库中，并且正在将数据解析为正确的表和字段。我再次求助各位大师来帮助解决问题

其中一个导入的字段有逗号分隔的值需要分隔。字符串中有 1 到 10 个可能的值。

 PHO,Rosgen,NRCS,EMAP,T-DL,YSI-DL 

我发现如果我使所有值的长度相同（比如 4 个字符），我可以在逗号之后获取第一个、最后一个和第一个来解析，但似乎无法正确提取中间值。

SELECT Left([FieldForms],InStr([FieldForms],",")-1) AS DEQ_SampleTypeID
FROM tblSiteVisit
UNION ALL
SELECT Mid([FieldForms],InStr([FieldForms],",")+1,4) AS DEQ_SampleTypeID
FROM tblSiteVisit
UNION ALL
SELECT Mid([FieldForms], 11, 4) AS DEQ_SampleTypeID
FROM tblSiteVisit
UNION ALL
SELECT Mid([FieldForms], 16, 4) AS DEQ_SampleTypeID
FROM tblSiteVisit
UNION ALL
SELECT Mid([FieldForms], 21, 4) AS DEQ_SampleTypeID
FROM tblSiteVisit
UNION ALL
SELECT Mid([FieldForms],InStrRev([FieldForms],",")-4,4) AS DEQ_SampleTypeID
FROM tblSiteVisit
UNION ALL
SELECT Right([FieldForms],InStr([FieldForms],",")-1) AS DEQ_SampleTypeID
FROM tblSiteVisit

如果我使用 InStrRev 或 Right 函数，我会得到重复，如果少于最大值，使用 Mid 函数也会导致空行。

有没有办法解析出这样的字符串，只从字符串中获取结果

Answer 1

将以下函数放入一个模块中：

   Function CountCSWords (ByVal S) As Integer
  ' Counts the words in a string that are separated by commas.

  Dim WC As Integer, Pos As Integer
     If VarType(S) <> 8 Or Len(S) = 0 Then
       CountCSWords = 0
       Exit Function
     End If
     WC = 1
     Pos = InStr(S, ",")
     Do While Pos > 0
       WC = WC + 1
       Pos = InStr(Pos + 1, S, ",")
     Loop
     CountCSWords = WC
  End Function

  Function GetCSWord (ByVal S, Indx As Integer)
  ' Returns the nth word in a specific field.

  Dim WC As Integer, Count As Integer, SPos As Integer, EPos As Integer
     WC = CountCSWords(S)
     If Indx < 1 Or Indx > WC Then
       GetCSWord = Null
       Exit Function
     End If
     Count = 1
     SPos = 1
     For Count = 2 To Indx
       SPos = InStr(SPos, S, ",") + 1
     Next Count
     EPos = InStr(SPos, S, ",") - 1
     If EPos <= 0 Then EPos = Len(S)
     GetCSWord = Trim(Mid(S, SPos, EPos - SPos + 1))
  End Function

然后，像这样在查询中添加一个字段：

MyFirstField: GetCSWord([FieldForms],1)

像这样放入另一个：

MySecondField: GetCSWord([FieldForms],2)

等等...根据您的需要。

Answer 2

此 VBA 代码从 tblSiteVisit 中的 FieldForms 读取文本值，将该文本拆分为子字符串，然后将每个子字符串存储在 DEQ_SampleTypeID在添加到 tblDestination 的新行中。

Dim astrItems() As String
Dim db As DAO.database
Dim i As Long
Dim qdf As DAO.QueryDef
Dim rs As DAO.Recordset
Dim strInsert As String

strInsert = "INSERT INTO tblDestination (DEQ_SampleTypeID)" & vbCrLf & _
    "VALUES ([array_item]);"

Set db = CurrentDb
Set rs = db.OpenRecordset("tblSiteVisit", dbOpenTable, dbOpenSnapshot)
Set qdf = db.CreateQueryDef(vbNullString, strInsert)
Do While Not rs.EOF
    astrItems = Split(rs!FieldForms, ",")
    For i = 0 To UBound(astrItems)
        qdf.Parameters("array_item") = astrItems(i)
        qdf.Execute dbFailOnError
    Next
    rs.MoveNext
Loop
rs.Close
Set rs = Nothing
Set qdf = Nothing
Set db = Nothing