//fill the order combobox datasource with the data from database by using dbcontext
private void Form1_Load(object sender, EventArgs e)
{
//display orders details and order when formloads from the database.
using (OrdersDataContext db = new OrdersDataContext()) //connect to db
{
orderIDComboBox.DataSource = from ord in db.Orders //fill the combobox i.e datasource with order id's from orders table
orderby ord.OrderID
select ord.OrderID;
}
}