Null DB fields causing an error

[Guest]

Below is the code I am using to display a list of values from a table row the
problem is some of these columns may be null. Currently when I execute this
code I get the following error: "Cast from type 'DBNull' to type 'String' is
not valid."

This error is caused by the null values. How can I avoid this error?

Dim i As Integer = QueueReader.GetOrdinal("CustomerId")

If QueueReader.Read() And Not QueueReader.IsDBNull(i) Then
lblJanuary.Text = QueueReader("January")
lblFebruary.Text = QueueReader("February")
lblMarch.Text = QueueReader("March")
lblApril.Text = QueueReader("April")
lblMay.Text = QueueReader("May")
lblJune.Text = QueueReader("June")
lblJuly.Text = QueueReader("July")
lblAugust.Text = QueueReader("August")
lblSeptember.Text = QueueReader("September")
lblOctober.Text = QueueReader("October")
lblNovember.Text = QueueReader("November")
lblDecember.Text = QueueReader("December")
End If


Thanks, Justin

 

[Karl Seguin]

isn't it possible that one of the months has a null value in it?

if so you need to check for null on each of them.

Karl

 

[Tarren]

For the fields that could contain NULL values, you must do a check for
DBNULL

Below is an example of one way.

For me I write a function for the page, so my code would look like the
following

Dim i As Integer = QueueReader.GetOrdinal("CustomerId")

If QueueReader.Read() And Not QueueReader.IsDBNull(i) Then
If Not IsDBNull(QueueReader("January")) Then lblJanuary.Text
= QueueReader("January")
If Not IsDBNull(QueueReader("February")) Then
lblFebruary.Text = QueueReader("February")
'And the rest would take similar form
End If