In an MS Access 2007 project report, I have the following (redacted) query:
SELECT SomeCol FROM SomeTable
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;