private void btnNavProp_Click(object sender, EventArgs e)
{
northwindEntities dc = new northwindEntities();
var query = from c in dc.Customers
where c.Orders.Count == 0
select c;
dataGridView2.DataSource = query.ToList();
}
private void btnWhereNot_Click(object sender, EventArgs e)
{
northwindEntities dc = new northwindEntities();
var query = from c in dc.Customers
where !(from o in dc.Orders
select o.CustomerID).Distinct().Contains(c.CustomerID)
select c;
dataGridView1.DataSource = query.ToList();
}