dilerim işinize yarar.
Modül kodu

Function DgTrh(Mtn As String) As String

Dim BlYr, BlYrBit As Integer

Dim StrTrh

BlYr = 0

    For x = 1 To 2

        BlYr = InStr(BlYr + 1, Mtn, "/")

    Next x

BlYrBit = InStr(BlYr + 1, Mtn, "/")

If BlYrBit = 0 Then BlYrBit = Len(Mtn & "")

BlYrBit = BlYrBit + 1 - BlYr



Mtn = Mid(Mtn, BlYr, BlYrBit)



    For x = 1 To BlYrBit

        If IsNumeric(Mid(Mtn, x, 1)) Then StrTrh = StrTrh & Mid(Mtn, x, 1)

    Next x

    

    StrTrh = Right(StrTrh, 2) & "." & Mid(StrTrh, 5, 2) & "." & Left(StrTrh, 4)

    DgTrh = StrTrh

End Function

güncelleme kodu

CurrentDb.Execute "UPDATE Tablo1 SET dogum_yili = DgTrh([kisi])"