[RESOLVED] How to check DBNull Value?

[zhtway1]

Hi,

I have a problem with verifying dbnull value. Actually I don't know the syntax.
Here is the code.

            If Not IsDBNull(Me.DeliveryReviewDataSet.Delivery(Me.CustomerIDListBox.SelectedIndex).Signature) Then

"Signature" is the image field (binary data).

Any help will be appreciated.
Thanks
zhtway

[zhtway1]

Hi,
I post it in the wrong place. don't know how to move to VB forum
zhtway

[Hack]

I post it in the wrong place. don't know how to move to VB forum

But I do...Moved From The CodeBank

[jmcilhinney]

There are various ways to check for NULL and the best way depends the circumstances. In your case, you're using a typed DataSet so it specifically provides methods for you to set a field to NULL and to determine if a field is NULL. First up, if you want the row selected in the ListBox:

Dim row As DeliveryDataRow = DirectCast(Me.DeliveryBindingSource.Current, DeliveryDataRow)
 
If row.IsSignatureNull() Then
    'Signature is NULL.
End If

The converse operation uses the SetSignatureNull method.

[zhtway1]

Hi,

Thanks for your reply.
I have to modify code from your reply as it showed up with errors.
Pls correct me if I am wrong.
Error is "Error:unable to cast object of type 'System.data.datarowview' to type 'DeliveryRow'.

            Dim row As DeliveryReviewDataSet.DeliveryRow = DirectCast(Me.DeliveryBindingSource.Current, DeliveryReviewDataSet.DeliveryRow)
            If row.IsSignatureNull() Then
                MsgBox("it is null")
            End If

Thanks again,
zhtway

[jmcilhinney]

Ah, sorry. That's the risk when typing straight into the forum rather than an IDE. It should actually be:

Dim row As DeliveryReviewDataSet.DeliveryRow = DirectCast(DirectCast(Me.DeliveryBindingSource.Current, DataRowView).Row, DeliveryReviewDataSet.DeliveryRow)

[zhtway1]

Hi,

Thanks for your help!
It solved.

rgds,
zhtway