Question

Some tables I am dealing with have null values and are throwing errors. So far ive tried a few solutions to deal with the nulls with no success.

Here are the code samples from my efforts so far;

If (r("datemodified").Equals(DBNull.Value)) Then
                datemodified = String.Empty
            Else
                datemodified = (r("datemodified"))
            End If

and;

If r.HasRows Then
                datemodified = (r("datemodified"))
            Else
                datemodified = String.Empty
            End If

and;

 If r("datemodified") = Nothing Then
                datemodified = String.Empty
            Else
                datemodified = (r("datemodified"))
            End If

and;

If r.IsDBNull("datemodified") Then
                datemodified = String.Empty
            Else
                datemodified = (r("datemodified"))

and via sql;

Select isnull(datemodified, '')

The end result is an IndexOutOfRangeException.

here is the sql;

select datemodified, maintainedby, email, hitcount from grouping where id = @footid

ps, i have ran the query and it is working ok (i.e all the cols exist)

Answer 1

To handle the null value in the code you can use the IsDBNull method:

Dim index As Integer = r.GetOrdinal("datemodified")
If r.IsDBNull(index) Then
   datemodified = String.Empty
Else
   datemodified = r(index)
End If

To handle the null value in the SQL you have to give the field a name, to be able to access it by name in the data reader:

select datemodified = isnull(datemodified, '')