VB.NET Newbie Need Help

[leachster]

Hello,

I am trying to calculate the sum of the columns and I keep getting the same error: "Object reference not set to an instance of an object." My code is listed below.


Dim ds As DataSet

Dim myTable As DataTable

'myTable = ds.Tables("Order Details")

' Declare an object variable.

'Dim objSum As Object

'objSum = ds.Tables("Order Details").Compute("Sum(UnitPrice)", "")

'lblTotalCost.Text = objSum

[jmcilhinney]

You haven't created a DataSet object. This:

Dim ds As DataSet

declares a variable that can refer to a DataSet object but it does not create a DataSet object. You need to invoke the constructor with the New keyword:

Dim ds As New DataSet

I suggest that you follow the Start VB.NET tutorial link in my signature and read at least the OOP section.

[leachster]

Thanks!!!