Preserving NULL values in a Double Variable

Question

I\'m working on a vb.net application which imports from an Excel spreadsheet.

If rdr.HasRows Then
        Do While rdr.Read()
            If rdr.GetValue(0).         


        

Answer 1

You need the question mark ? to let Double (or any value type) can store null (or Nothing). E.g.:

Dim num as Double? = Nothing

Note the ? mark.

To store in the db:

If num Is Nothing Then
  ... System.DBNull.Value ...
Else
  ... num ...
End If

or better:

If num.HasValue Then
  ... System.DBNull.Value ...
Else
  ... num.Value ...
End If