NullRsetError

strMyString=Clean(rdoResultset("MyVarCharColumn"))
'also convert Empty values as well, for use with Variants:

Public Function Clean(ByVal varData As Variant) As String
If IsNull(varData) Then
Clean = ""
ElseIf IsEmpty(varData) Then
Clean = ""
Else
Clean = CStr(varData)
End If
End Function