Generate random string in text field

This is one way, will work in Access VBA (which is an older basic than vb.net). It will generate a string with letters and numbers.

Sub test()

    Dim s As String * 8 'fixed length string with 8 characters
    Dim n As Integer
    Dim ch As Integer 'the character
    For n = 1 To Len(s) 'don't hardcode the length twice
        Do
            ch = Rnd() * 127 'This could be more efficient.
            '48 is '0', 57 is '9', 65 is 'A', 90 is 'Z', 97 is 'a', 122 is 'z'.
        Loop While ch < 48 Or ch > 57 And ch < 65 Or ch > 90 And ch < 97 Or ch > 122
        Mid(s, n, 1) = Chr(ch) 'bit more efficient than concatenation
    Next

    Debug.Print s

End Sub