Predmet:Re: Zabrana duplog unosa
  
  
  Evo ti funkcija za provjeru valjanosti oiba po zakonu 
http://www.regos.hr/...0OIB-a.pdf
Private Function KontrolnaZnamenka(ByVal s As String) As Long
    Dim i As Long, n As Long
    n = 10
    For i = 1 To Len(s)
        n = n + CLng(Mid(s, i, 1))
        n = n Mod 10
        If n = 0 Then n = 10
        n = n * 2
        n = n Mod 11
    Next
    n = 11 - n
    If n = 10 Then n = 0
    KontrolnaZnamenka = n
End Function
Public Function ProvjeriOIB(ByVal s As String) As Boolean
    On Error GoTo e
    If Len(s) <> 11 Then Exit Function
    If Mid(s, 11, 1) <> KontrolnaZnamenka(Mid(s, 1, 10)) Then Exit Function
    ProvjeriOIB = True
e:
End Function
Ulaz je 
ProvjeriOIB