Strip out non-numeric characters in SELECT

问题

In an MS Access 2007 project report, I have the following (redacted) query:

SELECT SomeCol FROM SomeTable

The problem is, that SomeCol apparently contains some invisible characters. For example, I see one result returned as 123456 but SELECT LEN(SomeCol) returns 7. When I copy the result to Notepad++, it shows as ?123456.

The column is set to TEXT. I have no control over this data type, so I can't change it.

How can I modify my SELECT query to strip out anything non-numeric. I suspect RegEx is the way to go... alternatively, is there a CAST or CONVERT function?

回答1:

You mentioned using a regular expression for this. It is true that Access' db engine doesn't support regular expressions directly. However, it seems you are willing to use a VBA user-defined function in your query ... and a UDF can use a regular expression approach. That approach should be simple, easy, and faster performing than iterating through each character of the input string and storing only those characters you want to keep in a new output string.

Public Function OnlyDigits(ByVal pInput As String) As String
    Static objRegExp As Object

    If objRegExp Is Nothing Then
        Set objRegExp = CreateObject("VBScript.RegExp")
        With objRegExp
            .Global = True
            .Pattern = "[^\d]"
        End With
    End If
    OnlyDigits = objRegExp.Replace(pInput, vbNullString)
End Function

Here is an example of that function in the Immediate window with "x" characters as proxies for your invisible characters. (Any characters not included in the "digits" character class will be discarded.)

? OnlyDigits("x1x23x")
123

If that is the output you want, just use the function in your query.

SELECT OnlyDigits(SomeCol) FROM SomeTable;

回答2:

There is no RegEx in Access, at least not in SQL. If you venture to VBA, you might as well use a custom StripNonNumeric VBA function in the SQL statement.

e.g. SELECT StripNonNumeric(SomeCol) as SomeCol from SomeTable

Function StripNonNumeric(str)
      keep = "0123456789"
      outstr = ""
      For i = 1 to len(str)
          strChar = mid(str,i,1)
          If instr(keep,strChar) Then
              outstr = outstr & strChar
          End If
      Next
      StripNonNumeric = outstr
  End Function

回答3:

You can do it all in a query, combining this question with your previous question, you get:

SELECT IIf(IsNumeric([atext]),
           IIf(Len([atext])<4,Format([atext],"000"),
               Replace(Format(Val([atext]),"#,###"),",",".")),
           IIf(Len(Mid([atext],2))<4,Format(Mid([atext],2),"000"),
               Replace(Format(Val(Mid([atext],2)),"#,###"),",","."))) AS FmtNumber
FROM Table AS t;

回答4:

Public Function fExtractNumeric(strInput) As String
' Returns the numeric characters within a string in
' sequence in which they are found within the string
Dim strResult As String, strCh As String
Dim intI As Integer
If Not IsNull(strInput) Then
    For intI = 1 To Len(strInput)
        strCh = Mid(strInput, intI, 1)
        Select Case strCh
            Case "0" To "9"
                strResult = strResult & strCh
            Case Else
        End Select
    Next intI
End If
fExtractNumeric = strResult

End Function

来源：https://stackoverflow.com/questions/12563701/strip-out-non-numeric-characters-in-select