VBA not recognizing Null value

Question

Working in MSAccess. I'm trying to toggle the visibility of a button based on the value of a text box. The form was created off of a query. I've made sure the value in the tbl_Manufacturer.Website is Null. But the code keeps validating as false and drops into the next set of code. What did I miss?

Private Sub Form_Load()

    If ([Forms]![frm_Asset]![tbl_Manufacturer.WebSite]) = Null Then
            
        btn_Hyperlink.Visible = False
    
    Else
        
        btn_Hyperlink.Caption = [Forms]![frm_Asset]![tbl_Manufacturer.WebSite]
        btn_Hyperlink.Visible = True
    
    End If

End Sub

-Jeff

score 3 · Answer 1 · answered Aug 12 '20 at 18:38

3

Nothing is ever equal to Null, since Null is a missing value. Something = Null is always going to return Null, which evaluates to false.

If you want to test if a field is null, use the IsNull function:

If IsNull([Forms]![frm_Asset]![tbl_Manufacturer.WebSite]) Then

answered Aug 12 '20 at 18:38

Erik A

31,639
12
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ISNULL! Thank you Erik, completely forgot that! – JMJ Aug 12 '20 at 18:41

score 0 · Answer 2 · answered Aug 12 '20 at 18:40

0

Try using IsNull instead:

If (IsNull([Forms]![frm_Asset]![tbl_Manufactuer.Website]) Then ......

Testing if a string is null

answered Aug 12 '20 at 18:40

Mr Rob

59
7

score -1 · Answer 3 · answered Aug 12 '20 at 22:58

-1

In addition to the IsNull option presented by other answers, you can simply compare to an empty string, since this is a text box:

If ([Forms]![frm_Asset]![tbl_Manufacturer.WebSite]) Is Not "" Then

answered Aug 12 '20 at 22:58

Psychoceramics

45
7

VBA not recognizing Null value

3 Answers3